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                   IN RE SANTIAGO G.*
                        (AC 36852)
             DiPentima, C. J., and Alvord and Bear, Js.
    Argued October 29, 2014—officially released January 6, 2015**

   (Appeal from Superior Court, judicial district of
    Stamford, Juvenile Matters, Heller, J. [neglect
 adjudication]; Hon. A. William Mottolese, judge trial
     referee [motion to revoke; motion to open].)
 Elizabeth K. Adams, for the appellant (respondent
mother).
  Michael Besso, assistant attorney general, with whom
were Lorri Kirk, assistant attorney general, and, on the
brief, George Jepsen, attorney general, and Gregory T.
D’Auria, solicitor general, for the appellee (petitioner).
  Joshua Michtom, assistant public defender, for the
minor child.
                         Opinion

  DiPENTIMA, C. J. In this uniquely unfortunate case,
the respondent mother, Melissa M.,1 appeals from the
judgment of the trial court denying her motion to revoke
the commitment of her minor child, Santiago G. (child),
and transfer custody and guardianship to a third person,
Maria G., who had cared for the child for the first three
years of his life. Specifically, she argues that the court
improperly (1) considered the best interests of the child
even though the original cause for commitment never
had existed, (2) found that it was in his best interests
to remain with his foster family,2 and (3) denied her
motion to open on the basis of newly discovered evi-
dence. The petitioner, the Commissioner of Children
and Families (commissioner), also advocates that the
child should be returned to the custody and guardian-
ship of Maria G. The child, through his attorney, and
the guardian ad litem, Attorney Brian D. Kaschel,3 dis-
agree and counter that the court properly considered
and weighed the best interests of the child in declining
to remove him from his foster family. We affirm the
judgment of the trial court.
   The unique circumstances of this case require a
detailed recitation of the facts. On October 10, 2012,
the child, then age three, was taken into the care and
custody of the commissioner pursuant to a ninety-six
hour hold. The child was returned to Maria G. the next
day after the court, Hon. A. William Mottolese, judge
trial referee, denied the ex parte motion filed by the
commissioner for an order of temporary custody. Judge
White denied a second ex parte motion for an order of
temporary custody on October 12, 2012. On October
16, 2012, the commissioner filed for a third ex parte
motion for an order of temporary custody on the basis
of the same facts. Specifically, the commissioner
alleged that the Department of Children and Families
(department) had received a report from the United
States Department of Homeland Security that Maria G.
and her husband possibly had purchased a child in
Guatemala and smuggled him into the United States on
June 14, 2009.4 This report also contained an allegation
that Maria G. had been physically aggressive with the
child.
   During an investigation by the department, Maria G.
stated that the mother of her former housekeeper
alerted her to a pregnant fourteen year old orphan in
Guatemala, later identified as the respondent, who
wanted to place her newborn baby. Maria G. admitted
to travelling to Guatemala, paying a physician to deliver
the baby and contacting a midwife to falsify information
so that she was listed as the biological mother. Maria
G. acknowledged using this false information to obtain
a birth certificate for the child that named her and her
husband as the biological parents. Last, Maria G. told
the investigator that she had used the false passport to
facilitate the return to the United States with her hus-
band and the child.
   On October 16, 2012, Judge Heller, finding that the
child was in immediate physical danger from his sur-
roundings, entered an order vesting the temporary care
and custody of him in the commissioner and scheduled
a subsequent hearing. The court sustained the order of
temporary custody after a hearing on October 25, 2012.
On November 15, 2012, the court adjudicated the child
neglected on the basis that he had been abandoned by
his biological parents, who were unknown at the time
of the hearing. At a hearing on December 6, 2012, the
assistant attorney general representing the department
informed the court that Maria G. had provided him with
the identity of the respondent and that the department
was in the process of verifying that she was the biologi-
cal mother of the child. On January 24, 2013, the court
rendered a default judgment against the biological
father for failing to appear in the proceedings. On Febru-
ary 14, 2013, the commissioner objected to Maria G.
being granted intervenor status and, thereafter, the
court denied her motion to intervene.
   At a hearing on June 6, 2013, counsel for the respon-
dent was present for the first time and the court
appointed Kaschel as guardian ad litem for the child.
Additionally, on that date the court received evidence
that the respondent was the biological mother of the
child.5 On June 28, 2013, the commissioner reversed
her position on Maria G. being granted intervenor status
after confirming that the respondent was the biological
mother who wanted Maria G. to raise the child.
   On September 12, 2013, the department presented a
permanency plan seeking a transfer of guardianship to
Maria G. and a concurrent termination of parental rights
and adoption by Maria G. The alternative plan was a
termination of the respondent’s parental rights and
adoption by the foster parents, who had been caring
for the child since December, 2012. On October 22,
2013, the respondent filed a motion captioned ‘‘Motion
to Revoke Commitment.’’ She alleged that the cause
for commitment of the child no longer existed and that
custody and guardianship of the child should be trans-
ferred to Maria G. in accordance with the respondent’s
wishes. Approximately two months later, the commis-
sioner filed a motion to open and set aside the judgment
adjudicating the child neglected on the basis of mutual
mistake. Specifically, the commissioner argued that the
parties had been mistaken in the belief that the identity
of the biological parents was unknown at the time of
the commitment, and that the child was the victim of
human trafficking. The commissioner asserted that it
was in the best interests of the child for the court to
open the adjudication of neglect and to set aside the
November 15, 2012 order of commitment.6
  Starting on January 16, 2014, and continuing for
almost four months over divers dates, the court, Hon.
A. William Mottolese, judge trial referee, held a hearing
on the motions filed by the respondent and the commis-
sioner. Marta Saavedra, a member of the department’s
intake unit, testified that on September 18, 2012, she
had received a referral from the United States Depart-
ment of Homeland Security alleging that Maria G. and
her husband participated in human trafficking and phys-
ically abused the child. The basis of this information
was an anonymous tip. During her interview with Saave-
dra, Maria G. lied and stated she did not have any
complications during her pregnancy with the child.
Maria also stated that she and her husband were the
biological parents of the child. Maria G. later revealed
the truth of how she had learned of the respondent’s
plight and eventually brought the child to the United
States.
  Maria G. herself testified that a family friend needed
a place to live and she permitted him to sleep in the
basement for a few days. She believed that this individ-
ual was the person responsible for contacting the
United States Department of Homeland Security after
she requested that he move out.7 Maria G. also testified
that she had pleaded guilty to a federal felony8 and as
part of her plea she agreed to leave the United States
and return to Argentina. She planned to take the child
with her and live with her family.
   After hearing from other witnesses, the court issued
an oral decision at the conclusion of the hearing. The
court first determined that the grounds for the commit-
ment no longer existed. It then turned to the issue of
whether the revocation of the commitment was in the
best interests of the child. ‘‘The court believes that the
burden of proof has been sustained and that the motion
to revoke the commitment should be denied. . . .
Now, my concerns are, and the reason that I believe
that it is in this child’s best interests that he remain
with [his foster parents] are: First, that a removal from
his present environment would be so harmfully trau-
matic to him that he would suffer far greater from that
trauma than he would suffer from any predictable, per-
ceivable harm that he will suffer in later life, whether
that’s when he reaches middle school age, at age ten,
whether he reaches what I always say is the toughest
age for an adolescent, and that’s age fourteen, or
whether it doesn’t hit him until he’s an adult, all of that
to me, the likelihood of that happening, which is not
certain, it’s not inevitably predictable. And I don’t think
I even heard it stated from an expert within a reasonable
degree of probability, but I am going to assume that
there is a distinct possibility that it will occur. That
harm does not outweigh the harm that I think will occur
to him from the removal. . . .
  ‘‘But it’s clear to me that from his use of the term, I
have two mommies, that the description that Dr. [David]
Mantell gave today is accurate. And that is that there
are two primary attachments here. . . . Now, whether
the attachment with [Maria G.] will ever be rekindled
or renewed, it certainly will never reach the same level
that it had, that it did in the past. There’s no question
about that.
   ‘‘So [Maria G.’s] stature as a primary attachment will
gradually diminish, and she will become a secondary
attachment, if—if even, if even that. And the [foster
family] will be become a stronger primary attachment.
And it’s clear to me from all the testimony from the
school people, from the therapist, that [the child] is
thriving in this environment, and that he will continue
to thrive. And it’s not just a question of making him
happy, it’s not just a question of doing what he requests
that we do, of catering to his whims and desires. After
all . . . he’s certainly not capable of making any kind
of a rational or mature judgment. But nevertheless, I
agree with the guardian ad litem that is, it is clearly in
his best interests that he continue to grow up in that
environment. . . . I mean, I have—I have a vision in
my mind of the kid, child being removed bodily, kicking
and screaming, and being taken out to visit [Maria G.]
because he’s learned that he’s going to be going back
to [Maria G.] I can’t assess the damage that would be
caused to him for that.
   ‘‘Next, in trying to determine what reunification
would be like with Maria G., I see, of course, a trip
to Argentina, and the establishment of the home in
Argentina, the development of relationships with family
and extended family, the making of new friends. I’m
going to presume that all of that is—is going to go—
would go smoothly, and would benefit him. But what
I don’t know is what’s the rest of the environment look
like down there?
   ‘‘There may be psychological, psychologists, thera-
pists. I don’t know that their level of competence is. I
don’t know whether they’re equipped, trained to deal
with this—this particular issue that this child faces,
which rarely occurs in the experience of any psycholo-
gist. I don’t know what kind of schools there are in
Argentina. I don’t know what the community consists
of down there, whether it’s appropriate for him or not.
. . . So these—these are the concerns that I have. And
these are the reasons why I don’t think reunification
with Maria G. is in his best interests. And that remaining
with the [foster family] is indeed in his best interests.’’
   On April 28, 2014, the commissioner filed a motion
for reconsideration. On May 6, 2014, the commissioner
filed a motion to open the judgment and introduce
newly discovered evidence, which the respondent sub-
sequently joined. The commissioner argued that Maria
G. would not be sentenced in her federal criminal case
until August, 2014, at the earliest, and therefore there
would be time to reintroduce the child to her before
she was to return to Argentina. The court denied the
motions to open and the relief requested in the motion
for reconsideration, and this appeal followed.9
                            I
  The respondent first claims that the court improperly
considered the best interests of the child even though
the original cause for commitment never had existed.
Specifically, she argues that General Statutes § 46b-129
(m)10 does not ‘‘contemplate that the court conduct a
best interests analysis where no cause for commitment
existed in the first place.’’ We conclude that the parties
and the court proceeded under the incorrect subsection
of § 46b-129; nevertheless, the court properly consid-
ered the best interests of the child in resolving the
respondent’s dispositional motion to transfer guardian-
ship to Maria G.11
   The case of In re Avirex R., 151 Conn. App. 820, 96
A.3d 662 (2014), is the appropriate starting point for our
analysis. In that case, the respondent mother appealed
from the judgment of the trial court transferring guard-
ianship of her minor child from the commissioner to
his paternal aunt.12 Id., 821–22. The child had been born
with opiates in his system. Id., 822. The commissioner
placed a ninety-six hour hold on him, filed a neglect
petition and moved for an order of temporary custody.
Id. The court granted the ex parte motion for an order
of temporary custody and the commissioner placed the
child with his paternal aunt following his release from
the hospital. Id., 823.
   The respondent in that case pleaded nolo contendere
to the neglect petition, but contested the disposition of
commitment. Id., 823. She also filed a motion for trans-
fer of guardianship seeking to have the child placed
with his maternal grandmother. Id. The court denied
this motion. Id. Approximately three months later, the
commissioner sought to revoke the commitment and
transfer guardianship to the paternal aunt. Id., 824. The
respondent filed an objection to the proposed transfer
of guardianship, and to have the court order a reunifica-
tion plan with her. Id., 824–25.
   The court granted the commissioner’s motion and
referred to § 46b-129 (m) as the applicable law. Id.,
825. Specifically, the court found that the cause for
commitment no longer existed because it was no longer
in the child’s best interests to continue with the commit-
ment. Id., 826. It further found that placement with the
paternal aunt was in the child’s best interests, rather
than placement and reunification with the respondent.
Id., 826–27.
   On appeal, the respondent argued that the court had
misapplied § 46b-129 (m) by failing to make the required
finding that the cause for commitment no longer existed
and by failing to apply the required presumption of
fitness contained in that particular subsection of § 46b-
129. Id., 827. We determined that the court improperly
used subsection (m) because the commissioner had not
sought to return the child to the respondent, but instead
had sought to transfer guardianship to a third party.
Id., 827–28. ‘‘That procedure is properly governed by
subjection (j) of § 46b-129.’’ Id., 828. We also determined
that because the court had engaged in the analysis
required by § 46b-129 (j),13 the judgment did not need
to be reversed. Id.
   In setting forth the rationale for our decision, we first
noted that resolution of the appeal required a harmoni-
zation of the subsections of § 46b-129 and certain rules
of practice, including Practice Book §§ 35a-16, 35a-12A
and 35a-20. In re Avirex R., supra, 151 Conn. App. 828.
We also observed that a court looks to the substance
of a motion filed to determine which statute applies.
Id., 830. We stated that ‘‘the only issue before the court
in this case was whether guardianship of Avirex should
be transferred to his paternal aunt.’’ Id., 831.
   We then explained the distinction between the two
subsections of § 46-129. ‘‘An obvious difference
between these two subsections is that subsection (j)
contains specific language referencing a transfer of
guardianship to a party other than the child’s or youth’s
parent or former legal guardian and sets forth a pre-
sumption as to the individuals, such as other relatives,
who should then be given custody, while subsection
(m) makes no mention of any individual other than
the [commissioner], a parent or the child’s attorney.
Instead, subsection (m) is focused only on whether
the child’s or youth’s commitment should be revoked
without reference to a transfer of guardianship to a
party other than the parent or former guardian. As a
matter of logic, if the child’s or youth’s commitment to
the [commissioner] is revoked by the court without a
concomitant transfer of guardianship to a third party,
then the child must be reunified with the parent or
former legal guardian (with or without protective super-
vision) as contemplated by the permanency plan option
set forth in § 46b-129 (k) (2) (A) (‘revocation of commit-
ment and reunification of the child or youth with the
parent or guardian’).
   ‘‘Accordingly, we conclude that the legislature
intended that a motion, like the one filed here by the
[commissioner], seeking to transfer guardianship of
a child or youth from the [commissioner] to an indi-
vidual other than the parent or former guardian,
should be adjudicated by the court pursuant to subsec-
tion (j) of § 46b-129. This conclusion is buttressed by
reference to Practice Book § 35a-16, which provides in
relevant part that ‘[u]nless filed by the commissioner
of the department of children and families, any modifi-
cation motion to return a child or youth to the custody
of the parent without protective supervision shall be
treated as a motion for revocation of commitment.’ ’’
(Emphasis added; footnotes omitted.) In re Avirex R.,
supra, 151 Conn. App. 832–33; see also In re A.R., 123
Conn. App. 336, 338–39, 1 A.3d 1184 (2010); cf. In re
Marcus S., 120 Conn. App. 745, 753–54, 994 A.2d 253
(court used § 46b-129 [m] where parent sought transfer
of guardianship from commissioner to himself), cert.
denied, 297 Conn. 914, 995 A.2d 955 (2010).
   We set forth the applicable test for granting a motion
to transfer guardianship under § 46a-129 (j). ‘‘[T]he
court must first determine whether it would be in the
best interest of the child for guardianship to be trans-
ferred from the [commissioner] to the proposed guard-
ian. See also Practice Book § 35a-12A . . . . In
considering what is in the best interest of the child,
subsection (j) creates a rebuttable presumption that
if the proposed guardian is a member of one of the
enumerated group of relatives or caregivers, such a
transfer is in the child’s best interest. . . . Subsection
(j) (3) of § 46b-129 also provides a rebuttable presump-
tion that if the proposed guardian is a relative of the
child, and is either licensed by the department as a
foster parent, or has temporary custody of the child
when the motion to transfer guardianship is heard by
the court, such a relative is presumed to be a suitable
and worthy person to assume legal guardianship.’’ (Cita-
tions omitted.) In re Avirex R., supra, 151 Conn. App.
834–35. Finally, we determined that ‘‘a motion to trans-
fer guardianship is simply dispositional in nature,
and does not require the court to review the underlying
cause for commitment, which has already been judi-
cially determined during an earlier phase of the pro-
ceeding.’’ (Emphasis added.) Id., 835.
   The reasoning of In re Avirex R. applies to the present
case. The October 22, 2013 motion filed by the respon-
dent, although captioned as a ‘‘Motion to Revoke Com-
mitment,’’ sought an order transferring custody and
guardianship of the child to Maria G., a third party who
does not fall within the ambit of § 46b-129 (m). ‘‘The
label on the motion, however, does not control our
analysis. We must look to the substance of the relief
sought by the motion rather than its form because [t]o
hold [a litigant] strictly to the label on his filing would
exalt form over substance.’’ (Internal quotation marks
omitted.) In re Cameron C., 103 Conn. App. 746, 751,
930 A.2d 826 (2007), cert. denied, 285 Conn. 906, 942
A.2d 414 (2008); see also In re Avirex R., supra, 151
Conn. App. 830. As a result, the court should have
treated this as a motion to transfer guardianship filed
pursuant to subsection (j) of § 46b-129. See In re Avirex
R., supra, 833. As such, it was dispositional in nature
and subject to a best interests analysis.14 Id., 834; In re
Averiella P., 146 Conn. App. 800, 804, 81 A.3d 272 (2013);
In re A.R., supra, 123 Conn. App. 341; see also Practice
Book § 35a-12A.
  The respondent’s appellate argument that the adjudi-
cation must be vacated and that the child must be
returned to Maria G. because the cause for commitment
never existed in the first place is premised on the use
of § 46b-129 (m). Because we have concluded that it
was error, albeit harmless, for the court to use that
subsection, this argument fails. As noted in In re Avirex
R., supra, 151 Conn. App. 834: ‘‘In order to properly
grant a motion to transfer guardianship . . . the court
must first determine whether it would be in the best
interest of the child for guardianship to be transferred
from the [commissioner] to the proposed guardian.’’
Because the court conducted a best interests analysis
as required by § 46b-129 (j), we conclude that the
respondent’s statutory argument must fail.
                            II
  The respondent next claims that the court’s best inter-
ests finding was clearly erroneous. Specifically, she
argues that the court improperly credited the conclu-
sions of David Mantell, a clinical psychologist. We con-
clude that the court’s best interests finding was
supported in the record, and therefore, was not
clearly erroneous.
   The following additional facts are necessary for our
discussion. The respondent called Rodolfo Rosado, a
psychologist, as an expert witness. Rosado had evalu-
ated both the child and Maria G. He subsequently spoke
with the foster parents. As to Maria G., he testified that
she was upset with the circumstances and ‘‘extremely
motivated’’ to regain custody. Testing revealed no sig-
nificant indications of any antisocial types of behavior
or any indications of substance abuse or mental illness.
Rosado described her as ‘‘fundamentally a loving, car-
ing, attentive parent.’’ Rosado evaluated the child during
June and July, 2013, and described him as having some
trouble sitting still and focusing and that these aspects
suggest the eventual emergence of either severe anxiety
or attention deficit disorder. Rosado testified that the
child had increased indications of being restless, impul-
sive and emotionally labile, or having a tendency to
overreact to situations. The child identified himself with
the surname of the foster parents, who Rosado
described as ‘‘naturally affectionate, intelligent, caring,
decent, good people . . . .’’
   During one test, Rosado asked the child to make up
stories based on various cards. Rosado explained that
his stories lacked heroic figures, indicating that he
looked ‘‘at the world as confused . . . [where] terrible
things can happen in your life with absolutely no expla-
nation and there is no one to provide protection or
security against those dangerous, ominous forces.’’
Rosado expressed concerns that taking the child from
his first parental figure, Maria G., without warning or
explanation ‘‘broke’’ him and that this psychological
injury would remain and present a problem later in life.15
Rosado indicated, however, that the child appeared to
have numerous strengths and that with the support of
others, he expected him to ‘‘do generally well.’’
   Rosado also explained that the child needed a narra-
tive, which he lacked, to understand what had happened
to him and to complete his sense of identity. Absent
this narrative to heal the damage to his sense of identity,
Rosado feared that a tragedy involving the child would
occur one day in the future.
   Rosado recommended that the child be placed in the
care of Maria G., even if she left the United States for
Argentina. Acknowledging the negative impact on both
the foster family and the child, Rosado opined that he
would be surrounded by extended family and there was
‘‘a fair prognosis of being in an environment where he
will be loved and healed and given an explanation of
everything that went on in the first five years of his life
that make sense to him.’’
    Mantell testified as an expert called by the attorney
for the child. He had evaluated the child on two occa-
sions in December, 2013. The child presented as a
‘‘[s]uper high-charged little boy, just lovely, sociable,
friendly, responsive, interested, alert, verbal.’’ Mantell
described the interactions between the child and the
foster parents that he witnessed as ‘‘[v]ery natural,
warm, mutually interested reactions. The whole time
they—it looked like a natural and very close parenting-
child set of relationships. Moved easily between parent
to parent, lots of spontaneous expression of affection
that he initiated to both of them for touch contact, and
hugs, and smiles, and touches of many kinds, and which
he received similarly. And also, a great deal of laughter
as they played word games, and invented other things
to keep themselves busy with the toys and equipment
in the office.’’ The child identified the foster family as
his family. He also showed a ‘‘great deal of mutual
knowledge and affection’’ with his foster brother, who
was one year older. In short, Mantell opined that the
foster family was the child’s psychological family.16
   Given the child’s prior experiences of being separated
from Maria G.’s husband, then from Maria G., followed
by an unsuccessful and upsetting first foster care place-
ment, Mantell stated that he had been compromised
developmentally and considered him to be an already
vulnerable child who also had some temperamental
characteristics that placed him at risk for attention defi-
cit disorder. As a result, Mantell indicated that the child
would not be able to understand and successfully inte-
grate the loss of his foster family. He further explained
that these types of losses have a cumulative effect, and
therefore the greater the number of losses, the greater
the deficits in the future. Additionally, Mantell expected
that impact of the prior losses of Maria G.’s husband,
and then Maria G. herself to lessen for the child due
to his age when those events had occurred.17 Mantell
also explained that while the child had two primary
attachments, his attachment to Maria G. would decrease
in significance over time.
   Mantell agreed that a narrative would be beneficial
to the child and stated that one should be provided to
him at age ten. He noted that a narrative was being
developed with the foster family as evidenced by their
celebration of his one year anniversary with them in
December, 2013. The child, as he grew older, would
seek for a more advanced cognitive narrative to explain
the events, but he likely had overcome a substantial
portion of the emotional trauma of the removal from
Maria G. Specifically, he stated: ‘‘I think he has already
done the emotional work of processing that loss. I think
that that wound is already substantially healed. I think
he has already moved on significantly. And in his emo-
tional world, left that prior world behind. . . . I think
[that losing his world with the foster family] will be a
devastating impact. I don’t—I don’t know how he will
deal with that.’’ Mantell later clarified that, in his opin-
ion, this devastation would have a long lasting effect
on the child. Last, he stated that he did not know of
any way that returning the child back to Maria G. would
be better for him.
   The respondent presented Ilene Grueneberg, a psy-
chologist, as an expert and rebuttal witness. In prepara-
tion for her testimony, she reviewed the reports filed
by both Rosado and Mantell, as well as their testimony
in this case. She observed that Rosado and Mantell
differed as to their descriptions of whether the child
had a primary attachment to Maria G. and the impact
of removing him from his foster family’s home.
Grueneberg opined that returning the child to Maria G.
would allow him ‘‘to heal and understand, and hopefully
integrate some of the events that have occurred in a
more positive way.’’ She concluded that placing the
child with Maria G. was ‘‘really the primary and perhaps
the only way to—for him to resolve what has occurred,
given that he has that opportunity. . . . In this case,
he has the opportunity to heal that wound, to have
some other narrative for what’s happened to him. The
absence of narrative is very damaging. So it allows him
not only to know that, but to repair that with her.’’
   We note that: ‘‘Questions of custodial placement gen-
erally are resolved by a factbound determination of
what is in the best interest of the child . . . as shown
by a fair preponderance of the evidence. . . . To deter-
mine whether a custodial placement is in the best inter-
est of the child, the court uses its broad discretion to
choose a place that will foster the child’s interest in
sustained growth, development, well-being, and in the
continuity and stability of [his] environment. . . . We
have stated that when making the determination of what
is in the best interest of the child, [t]he authority to
exercise the judicial discretion under the circumstances
revealed by the finding is not conferred upon this court,
but upon the trial court, and . . . we are not privileged
to usurp that authority or to substitute ourselves for
the trial court. . . . Nothing short of a conviction that
the action of the trial court is one which discloses a
clear abuse of discretion can warrant our interference.
. . . [G]reat weight is given to the judgment of the trial
court because of [the court’s] opportunity to observe
the parties and the evidence. . . . [Appellate courts]
are not in a position to second guess the opinions of
witnesses, professional or otherwise, nor the observa-
tions and conclusions of the [trial court] when they are
based on reliable evidence.’’ (Internal quotation marks
omitted.) In re Sena W., 147 Conn. App. 435, 447–48,
82 A.3d 684 (2013); see also In re Anthony A., 112 Conn.
App. 643, 653–54, 963 A.2d 1057 (2009).
   The respondent specifically argues that the court’s
findings based on Mantell’s testimony were clearly erro-
neous and that instead the court should have credited
the expert testimony from Rosado and Grueneberg. ‘‘We
do not examine the record to determine whether the
trier of fact could have reached a conclusion other than
the one reached . . . nor do we retry the case or pass
upon the credibility of the witnesses. . . . The determi-
nations reached by the trial court . . . will be dis-
turbed only if [any challenged] finding is not supported
by the evidence and [is], in light of the evidence in the
whole record, clearly erroneous.’’ (Internal quotation
marks omitted.) In re Cameron C., supra, 103 Conn.
App. 757.18
   The respondent challenges the court’s reliance on
Mantell’s opinion that the child formed a second pri-
mary attachment to the foster mother and removal from
that home would cause greater harm than ending his
relationship with Maria G. She further points to the
testimony of Rosado and Grueneberg as more persua-
sive. Acceptance of this argument, however, would be
contrary to our case law. ‘‘It is well established that
[i]n a case tried before a court, the trial judge is the
sole arbiter of the credibility of the witnesses and the
weight to be given specific testimony. . . . The credi-
bility and the weight of expert testimony is judged by
the same standard, and the trial court is privileged to
adopt whatever testimony [it] reasonably believes to
be credible. . . . On appeal, we do not retry the facts
or pass on the credibility of the witnesses. . . . It is
the quintessential function of the fact finder to reject
or accept certain evidence, and to believe or disbelieve
any expert testimony. . . . The trier may accept or
reject, in whole or in part, the testimony of an expert
offered by one party or the other.’’ (Internal quotation
marks omitted.) In re Rafael S., 125 Conn. App. 605,
611–12, 9 A.3d 417 (2010); see also In re Juvenile Appeal
(Anonymous), 177 Conn. 648, 668, 420 A.2d 875 (1979)
(psychological testimony from professionals is rightly
accorded great weight and appellate courts not in posi-
tion to second-guess opinions of expert witness).
   The court, in making the best interests determina-
tion,19 was free to credit the testimony and opinion of
Mantell over Rosado and Grueneberg. See In re Cesar
G., 56 Conn. App. 289, 296–97, 742 A.2d 428 (2000). We
disagree that the court’s reliance on Mantell’s position
was clearly erroneous. Accordingly, the respondent’s
claim fails.
                           III
   The respondent next claims that the court improperly
denied her motion to open on the basis of newly discov-
ered evidence.20 Specifically, she argues that once it
became known that Maria G.’s sentencing in her federal
criminal case would be postponed and thus a graduated,
transitional return with the child would be possible,
the court should have granted the motion to open the
judgment. We disagree.
  On May 6, 2014, the commissioner, pursuant to Gen-
eral Statutes § 52-212a,21 filed a motion to open the
judgment to allow the introduction of newly discovered
evidence. In this motion, the commissioner argued that
the decision was ‘‘made in significant part based on the
evidence introduced at the time of trial that [Maria G.]
was going to be sentenced in Federal Court on May 2,
2014, and would likely be deported to Argentina within
several weeks after the sentencing.’’ The department
subsequently learned that the sentencing date had been
continued until August, 2014, at the earliest. The com-
missioner further argued that this additional time would
permit the child to return to the custody and care of
Maria G. in a graduated, transitional manner. On May 22,
2014, the respondent joined the commissioner’s motion.
   The following facts are necessary for our discussion.
On May 27, 2014, the court held a hearing on the motion
to open. The assistant attorney general claimed that
the court’s decision was based in large part on the lack
of time to introduce the child back into Maria G.’s life
and that her sentencing had been ‘‘pushed off’’ until
sometime after August.22 The court then issued an oral
decision denying the motion to open. It stated that the
commissioner had taken a ‘‘subsidiary finding and made
it the primary finding.’’ In order words, the period of
time before Maria G. would leave the United States was
not the primary reason for the court’s determination
that the best interests of the child were to remain with
the foster family. The court’s decision set forth two
primary reasons for denying the motion to transfer
guardianship. First, the court found that the present
harm of removing the child from the foster family out-
weighed any potential future harm. Second, the court
had a significant lack of information regarding the psy-
chological resources available to the child in Argentina.
  ‘‘A court may grant a motion for a new proceeding
based on newly discovered evidence if the movant
establishes by a preponderance of the evidence, that:
(1) the proffered evidence is newly discovered, such
that it could not have been discovered earlier by the
exercise of due diligence; (2) it would be material on
a new [proceeding]; (3) it is not merely cumulative; and
(4) it is likely to produce a different result in a new
[proceeding]. . . . It is within the discretion of the trial
court to determine, upon examination of all the evi-
dence, whether the [movant] has established substan-
tial grounds for a new [proceeding], and the judgment
of the trial court will be set aside on appeal only if it
reflects a clear abuse of discretion.’’ (Internal quotation
marks omitted.) Grasso v. Grasso, 153 Conn. App. 252,
265, 100 A.3d 996 (2014); see also Worth v. Korta, 132
Conn. App. 154, 160–61, 31 A.3d 804 (2011), cert. denied,
304 Conn. 905, 38 A.3d 1201 (2012).
  The court did not abuse its discretion in denying the
motion to open filed by the commissioner and joined
by the respondent. It explained that the timing of Maria
G.’s departure from the United States was not the pri-
mary focus of its best interests determination.23 It is
clear that the court concluded that the delay in sentenc-
ing would not have produced a different result in a new
proceeding. This claim, therefore, fails.
   As a final matter, we note the following statements
made over the course of Rosado’s testimony that com-
pellingly summarized the unfortunate nature of this
case. ‘‘My fear today is that we may have damaged [the
child] deeply and almost irreparably. And not only the
[child] but if you were to design a way to deeply damage
two children and two families, you couldn’t have done
a better job than the way this situation has evolved.
. . . [T]hese things happen to keep it going and sub-
stantiate it. [N]o matter what you do it is going to be
damaging. . . . No matter what you do at this point
very, very significant damage has been done . . . to
[the child], to [Maria G.], to the current foster parents,
and to their son . . . . The damage has been done by
us collectively with the best of intentions.’’
   The judgment is affirmed.
   In this opinion the other judges concurred.
   * In accordance with the spirit and intent of General Statutes § 46b-142
(b) and Practice Book § 79a-12, the names of the parties involved in this
appeal are not disclosed. The records and papers of this case shall be open
for inspection only to persons having a proper interest therein and upon
order of the Appellate Court.
   ** January 6, 2015, the date that this decision was released as a slip
opinion, is the operative date for all substantive and procedural purposes.
   1
     We refer in this opinion to Melissa M. as the respondent.
   2
     The foster family is comprised of a mother, father and a brother who
is approximately one year older than the child.
   3
     In accordance with Practice Book § 67-3, Kaschel, through his attorney,
filed a letter adopting the position of the child in this appeal.
   4
     Maria G. testified that she and her husband separated in February, 2012.
   5
     In the June 6, 2013 hearing, the court noted that a February 28, 2013
hearing had been marked off and a hearing scheduled for May 6, 2013 was
postponed as the DNA test results were pending. The DNA test results were
received on May 30, 2013. It appears, therefore, that the department made
diligent efforts to confirm that the respondent is the biological parent of
the child. We also note that the respondent has been in Guatemala during
the entirety of these proceedings and never has been present in court.
   6
     The court denied the commissioner’s motion to open on April 22, 2014.
On April 28, 2014, the commissioner moved for reconsideration. She argued
that in October, 2012, ‘‘the parties were under the mistaken belief that the
identities of the birth parents [were] unknown and could not be ascertained.
This mistake was buttressed by the allegation of human trafficking. At the
time those orders were entered, neither [the department] nor the child had
any information related to the identity of the biological parents and the
particular details about the custodial transfer. Only after the November 15,
2012 neglect adjudication and order of commitment did the identities of the
parents become known to the parties. Subsequently, the [department] was
able to verify that the [respondent] actively endorsed [Maria G.] as the de
facto parent for her son and continues to want him placed in [Maria G.’s]
physical custody.’’
   The court granted the commissioner’s motion for reconsideration but
denied the relief requested. It determined that ‘‘[m]utual mistake, no matter
how clear it is—and I don’t think it’s that clear here at all—does not trump
best interests by any means. Mutual mistake is an equitable principle that
allows for the court to work fairness, equity and justice. It would not be
fair, equitable and just to take action that was inimitable to the best interests
of the child. That’s why that principle does not prevail here.’’
   On August 21, 2014, this court ordered the department to file a brief
presenting its position on the issue raised by the respondent. In its appellate
brief, the department advocates for a departure from the abuse of discretion
standard of review in favor of plenary review due to the unique circum-
stances of this case. The department further explains the mutual mistake
as the ‘‘later-disproven concern about human trafficking and, in hindsight,
the state’s unnecessary and unfortunate intervention into the life of [Maria
G.’s] family.’’
   We do not depart from the abuse of discretion standard. ‘‘We do not
undertake a plenary review of the merits of a decision of the trial court to
grant or to deny a motion to open a judgment. . . . In an appeal from a
denial of a motion to open a judgment, our review is limited to the issue
of whether the trial court has acted unreasonably and in clear abuse of its
discretion. . . . In determining whether the trial court abused its discretion,
this court must make every reasonable presumption in favor of its action.
. . . The manner in which [this] discretion is exercised will not be disturbed
so long as the court could reasonably conclude as it did. . . . A court’s
determinations as to . . . whether there has been a mutual mistake are
findings of fact that we will not disturb unless they are clearly erroneous.’’
(Citation omitted; internal quotation marks omitted.) Terry v. Terry, 102
Conn. App. 215, 222–23, 925 A.2d 375, cert. denied, 284 Conn. 911, 931 A.2d
934 (2007). The court did not abuse its discretion by remaining focused on
the best interests of the child. We also reject the respondent’s appellate
argument that the court erred in declining to consider the motion to open
as a result of mutual mistake before undertaking a best interests analysis.
   7
     There was evidence before the court that Maria G. had rejected the
sexual advances of the family friend, and he had retaliated by reporting her
to the authorities.
   8
     The United States District Court for the District of Connecticut accepted
the guilty plea of Maria G. on November 26, 2013. Specifically, she pleaded
guilty to one count of conspiracy to unlawfully bring an alien child into the
United States in violation of 8 U.S.C. § 1324 (a) (1) (A) (v) (I). As of October
29, 2014, the date of oral argument before this court, she had not been
sentenced by the federal court.
   9
     The attorney for the child argues that this appeal was not taken from a
final judgment and not ripe, and therefore we lack subject matter jurisdiction
to consider its merits. We disagree. The reasoning found in cases such as
In re Shamika F., 256 Conn. 383, 404–405, 773 A.2d 347 (2001), Taff v.
Bettcher, 243 Conn. 380, 386–87, 703 A.2d 759 (1997), Madigan v. Madigan,
224 Conn. 749, 754–55, 620 A.2d 1276 (1993), and In re Todd G., 49 Conn.
App. 361, 363–65, 713 A.2d 1286 (1998), leads us to conclude that an immedi-
ate appeal is necessary to protect the rights attendant to the parent-child
relationship in this case.
   10
      General Statutes § 46b-129 (m) provides: ‘‘The commissioner, a parent
or the child’s attorney may file a motion to revoke a commitment and, upon
finding that cause for commitment no longer exists, and that such revocation
is in the best interests of such child or youth, the court make revoke the
commitment of such child or youth. No such motion shall be filed more
often than once every six months.’’
   11
      The respondent also appears to contend that because there had not
been a substantial showing at the temporary custody hearing that the child
was in immediate physical danger, it was error to sustain the order of
temporary custody. Counsel for the respondent made no effort to appeal
from the order of temporary custody and we decline to consider an untimely
challenge to that issue. See In re Shamika F., 256 Conn. 383, 408, 773 A.2d
347 (2001).
   12
      We acknowledge that the trial court did not have benefit of our decision
in In re Avirex R., supra, 151 Conn. App. 820, which was released on July
16, 2014.
   13
      General Statutes § 46b-129 (j) (3) provides in relevant part: ‘‘If the court
determines that the commitment should be revoked and the child’s . . .
legal guardianship . . . should vest in someone other than the respondent
parent, parents or former guardian . . . there shall be a rebuttable presump-
tion that an award of legal guardianship . . . upon revocation to . . . any
relative who is licensed as a foster parent for such child or youth, or who
is, pursuant to an order of the court, the temporary custodian of the child
or youth at the time of the revocation . . . shall be in the best interests of
the child or youth and that such relative is a suitable and worthy person
to assume legal guardianship . . . . The presumption may be rebutted by
a preponderance of the evidence that an award of legal guardianship to
. . . such relative would not be in the child’s . . . best interests and such
relative is not a suitable and worthy person. . . .’’
   14
      ‘‘To determine whether a custodial placement is in the best interest of
the child, the court uses its broad discretion to choose a place that will
foster the child’s interest in sustained growth, development, well-being, and
in the continuity and stability of [his] environment.’’ (Internal quotation
marks omitted.) In re Karl J., 110 Conn. App. 22, 26, 854 A.2d 231, cert.
denied, 289 Conn. 954, 961 A.2d 420 (2008).
   15
      During cross-examination, Rosado noted that the child also had sus-
tained a significant psychological blow when Maria G. separated from her
husband and the child did not have a full understanding of why the husband
no longer was involved in his life.
   16
      Mantell further expounded that the foster family ‘‘are the people who
provide [the child] with his sense of identity and security. He sees his future
with them. And I think it would be inexplicable for him if he were to be
removed from that home, and I think that a removal would create a devasta-
ting, psychological, developmental crisis for him. And I think it would trau-
matize him very severely.’’
   17
      Mantell noted that this concept of developmental amnesia would not
apply if the court was to remove the child from the foster family because
of his present age.
   18
      Our opinion in In re Cameron C., supra, 103 Conn. App. 757, an appeal
from a revocation of the commitment of a child to the department and a
reinstatement of guardianship in the father, referred to the clear and convinc-
ing standard of proof. Our Supreme Court subsequently clarified that the
fair preponderance standard applies in temporary custody and neglect pro-
ceedings, including dispositional proceedings. Fish v. Fish, 285 Conn. 24,
73–74, 939 A.2d 1040 (2008); see also In re Severina D., 137 Conn. App.
283, 293–94, 48 A.3d 86 (2012); In re Kamari C-L., 122 Conn. App. 815,
824–25, 2 A.3d 13, cert. denied, 298 Conn. 927, 5 A.3d 487 (2010).
   19
      ‘‘Although we often consider the testimony of mental health experts
. . . such expert testimony is not a precondition of the court’s own factual
judgment as to the child’s best interest.’’ (Internal quotation marks omitted.)
In re Kyara H., 147 Conn. App. 829, 852, 83 A.3d 1249, cert. denied, 311
Conn. 923, 86 A.3d 466 (2014).
   20
      The attorney for the minor child argues that the denial of the motion
did not constitute a final judgment for purposes of appeal. We have stated
that the denial of a motion to open the judgment is an appealable final
judgment. See Ryan v. Vera, 135 Conn. App. 864, 868, 43 A.3d 221 (2012);
Mailly v. Mailly, 13 Conn. App. 185, 188, 535 A.2d 385 (1988).
   21
      General Statutes § 52-212a provides: ‘‘Unless otherwise provided by law
and except in such cases in which the court has continuing jurisdiction, a
civil judgment or decree rendered in the Superior Court may not be opened
or set aside unless a motion to open or set aside is filed within four months
following the date on which it was rendered or passed. The continuing
jurisdiction conferred on the court in preadoptive proceedings pursuant to
subsection (o) of section 17a-112 does not confer continuing jurisdiction
on the court for purposes of reopening a judgment terminating parental
rights. The parties may waive the provisions of this section or otherwise
submit to the jurisdiction of the court, provided the filing of an amended
petition for termination of parental rights does not constitute a waiver of
the provisions of this section or a submission to the jurisdiction of the court
to reopen a judgment terminating parental rights.’’
  22
     The assistant attorney general also sought to introduce additional evi-
dence in the form of a home study conducted by the Argentinian Consulate
of the home of Maria G.’s mother and the ability to obtain an Argentinian
passport for the child. The latter documents were in Spanish without an
English translation; accordingly, the court refused to consider them. The
respondent did not challenge on appeal this aspect of the court’s ruling on
the motion to open.
  23
     We also note that during the hearing on the motion for reconsideration,
the court stated: ‘‘The primary reason was not because there was insufficient
time to effectuate a gradual and meaningful reunification. The primary rea-
son was that it was clearly, clearly in the court’s mind in the child’s best
interests that he remain with the [foster family].’’
