
562 N.W.2d 254 (1997)
221 Mich. App. 683
In the Matter of Crystal Lee HILL, Minor.
Loree Cheryl HILL, Petitioner-Appellee,
v.
Paul A. SIENKIEWICZ, Jr., Respondent-Appellant.
Docket No. 195806.
Court of Appeals of Michigan.
Submitted December 17, 1996, at Detroit.
Decided February 21, 1997, at 9:30 a.m.
Released for Publication April 29, 1997.
*256 Christopher Pencak, Warren, for petitioner-appellee.
Lord & Guilliat by Stephen M. Guilliat, Port Huron, for respondent-appellant.
Before MARK J. CAVANAGH, P.J., and REILLY and C.D. CORWIN[*], JJ.
*255 MARK J. CAVANAGH, Presiding Judge.
Respondent, Paul A. Sienkiewicz, Jr., appeals as of right a probate court order terminating his parental rights to his daughter, Crystal L. Hill, pursuant to § 51(6) of the Adoption Code, M.C.L. § 710.51(6); M.S.A. § 27.3178(555.51)(6). We affirm.
Respondent and petitioner, Loree C. Hill, are the parents of Crystal Hill. Crystal was born on April 17, 1984, when respondent was seventeen years old and petitioner was sixteen years old. In 1995, petitioner married Terry Kaltz. On November 7, 1995, petitioner and Terry Kaltz filed a petition for a *257 stepparent adoption, seeking authorization for Terry Kaltz to adopt Crystal. On the same day, petitioner filed a petition seeking termination of respondent's parental rights to Crystal pursuant to § 51(6) of the Adoption Code. A termination hearing was held on April 25, 1996.
At the hearing, petitioner testified that respondent attended prenatal classes with her, but then denied paternity after Crystal was born. However, a judgment of filiation was entered on October 7, 1985, naming respondent as the father of Crystal. On that same date, a judgment of support was entered. The support order provided that respondent was responsible for supporting Crystal, but stated that respondent's responsibility for support would be held in abeyance until petitioner again became a recipient of public assistance. Petitioner has not received public assistance since the support order was entered. The support order also required respondent to pay confinement expenses of $862.21 and blood testing fees of $395. In addition, respondent was responsible "for all reasonable and necessary medical, hospital, dental, optical, and pharmaceutical expenses incurred on behalf of said child." Petitioner testified that respondent never paid the confinement and blood-testing fees as mandated by the support order, never paid for any of Crystal's medical expenses, and has not contributed "a dime" toward Crystal's support.
Petitioner stated that respondent had seen Crystal approximately six times, with most of the visits occurring before the child's first birthday. According to petitioner, during those visits, respondent was focused on trying to renew their relationship, rather than on his daughter. Petitioner also testified that respondent threatened to kill her, to commit suicide, and to take Crystal away from her. Because petitioner was afraid of respondent, she refused to allow him to visit unless her mother was present. Respondent did not like this arrangement and ceased visitation, although he did see Crystal once in 1991. Crystal has never received any cards or gifts from respondent.
Crystal testified that she does not remember ever seeing respondent. In addition, she has never received any cards, gifts, or telephone calls from him, and she has no feelings of love and affection for him. Crystal wishes to be adopted by Terry Kaltz.
Paula Klimas, respondent's sister, testified that respondent visited Crystal frequently after the child was born. For several years after the relationship of petitioner and respondent ended, respondent was unable to see Crystal because he did not know where petitioner was. Respondent lived with Klimas for nine months beginning in June 1990, and he saw Crystal once during this period. Klimas claimed that respondent attempted to visit Crystal on numerous other occasions while he was living with her, but petitioner denied him permission.
Respondent testified that he lived with petitioner at her mother's house shortly after Crystal was born. Respondent paid rent and contributed toward the bills during this time. Respondent claimed that petitioner's mother forced him to leave after he lost his job, but he continued to see Crystal on a continuous basis until 1985, when he was incarcerated for breaking and entering. After his release, respondent violated his probation and was resentenced to two to fifteen years' imprisonment. Respondent maintained that, while in prison, he sent cards and gifts to Crystal at petitioner's mother's house, but has never received any reply. After respondent was paroled in 1990, he was initially allowed to see Crystal, but then petitioner and her mother denied him visitation. Respondent conceded that he has never made any child support payments and stated that he did not pay the medical bills and blood-testing expenses required by the 1985 support order because he did not have the money.
Respondent admitted writing a letter to petitioner's mother, dated March 11, 1996, which contained the following passage:
If she [petitioner] would Rather ignore this letter as she does all the others I have sent, then tell her I aint [sic] giving up nothing! Her man and herself can try some more sneaky underhand sh__, and get ready to pay extensive legal fees.
Respondent denied writing two other threatening letters, including one addressed to petitioner *258 that carried the salutation, "Dear Bitch, I hate you!"
At the conclusion of the hearing, the probate court ordered the parties to file written closing arguments. The court granted respondent's request to submit Department of Corrections disbursement records documenting any gifts or letters sent from prison. The only record that accompanied respondent's written closing argument was for a single disbursement from respondent to Crystal on March 2, 1996.
On May 22, 1996, the trial court issued a written opinion terminating respondent's parental rights pursuant to M.C.L. § 710.51(6); M.S.A. § 27.3178(555.51)(6). The court found that clear and convincing evidence had been presented that respondent "has substantially failed in his obligations to Crystal Lee Hill for a period of two years prior to the filing of this petition." The court noted that the statute does not specifically provide that the two-year period must be the two years immediately preceding the filing of the petition and concluded that any two-year period preceding the filing of the petition would be sufficient. This appeal ensued.

I

A
Respondent first argues that the probate court erred in ruling that the two-year statutory period referred to in M.C.L. § 710.51(6); M.S.A. § 27.3178(555.51)(6) can mean any two-year period before the filing of the petition. The statute provides:
If the parents of a child are divorced, or if the parents are unmarried but the father has acknowledged paternity or is a putative father who meets the conditions in section 39(2) of this chapter, and if the party having legal custody of the child subsequently marries and that parent's spouse petitions to adopt the child, the court upon notice and hearing may issue an order terminating the rights of the other parent if both of the following occur:
(a) The other parent, having the ability to support, or assist in supporting, the child, has failed or neglected to provide regular and substantial support for the child or if a support order has been entered, has failed to substantially comply with the order, for a period of 2 years or more before the filing of the petition.
(b) The other parent, having the ability to visit, contact, or communicate with the child, has regularly and substantially failed to or neglected to do so for a period of 2 years or more before the filing of the petition. [M.C.L. § 710.51(6); M.S.A. § 27.3178(555.51)(6).]
Statutory interpretation is a question of law that, on appeal, is reviewed de novo for error. The primary goal of judicial interpretation of statutes is to ascertain and give effect to the intent of the Legislature. Statutory language should be construed reasonably, keeping in mind the purpose of the act. Because the Adoption Code is in derogation of the common law, its provisions must be strictly construed. In re Schnell, 214 Mich.App. 304, 309-310, 543 N.W.2d 11 (1995).
This Court has recently held that the applicable two-year statutory period "commence[s] on the filing date of the petition and extend[s] backwards from that date for a period of two years or more." In re Halbert, 217 Mich.App. 607, 612, 552 N.W.2d 528 (1996). Thus, the probate court erred when it concluded that § 51(6) refers to any two-year period before the filing of the petition.
Petitioner contends that, notwithstanding Halbert, "principles of res judicata and stare decisis require that Judge Spillard's decision stand." Petitioner's reliance on these two doctrines is misplaced. The purpose of the doctrine of res judicata is to avoid relitigation of claims. Res judicata operates to bar a subsequent action between the same parties when the facts or evidence essential to maintenance of the two lawsuits are identical and the issues and parties or privies are identical. Ozark v. Kais, 184 Mich.App. 302, 307-308, 457 N.W.2d 145 (1990). Because no subsequent lawsuit is involved in the present case, the doctrine of res judicata is not applicable.
Petitioner's stare decisis argument is predicated on the assertion that Halbert is contrary to this Court's prior decision in In re *259 Colon, 144 Mich.App. 805, 377 N.W.2d 321 (1985). In Colon, which involved facts similar to those in the present case, this Court looked to the two-year period before the respondent's incarceration. However, the Halbert panel specifically discussed Colon and expressly concluded that it did not constitute meaningful authority for a contrary proposition. See Halbert, supra at 614, 552 N.W.2d 528. Moreover, even if the decisions in Colon and Halbert are contradictory, we are bound by Administrative Order No. 1996-4 to follow the interpretation set forth in Halbert.
Furthermore, the general rule in Michigan is that appellate court decisions are to be given full retroactivity unless limited retroactivity is justified. Moorhouse v. Ambassador Ins. Co. Inc., 147 Mich.App. 412, 420-421, 383 N.W.2d 219 (1985). A decision that interprets a preexisting statute should be given full retroactive effect, even though the interpretation presented may involve a question of first impression. Thus, we must give Halbert full retroactive effect, and its interpretation of M.C.L. § 710.51(6); M.S.A. § 27.3178(555.51)(6) is controlling in the present case.
Petitioner also contends that respondent does not have standing to oppose termination under M.C.L. § 710.51(6); M.S.A. § 27.3178(555.51)(6). Petitioner contends that respondent does not fall within the parameters of the statute because (1) he was never married to petitioner, and hence never divorced from her; (2) he denied paternity after Crystal was born; and (3) he is not a putative father who meets the conditions in § 39(2).[1] We find petitioner's argument to be flawed, both factually and logically. First, although respondent did initially deny paternity, an order of filiation was entered on January 9, 1985, naming respondent as the father of Crystal. Second, it was petitioner who invoked § 51(6) as a statutory basis for terminating respondent's parental rights. Petitioner cannot attempt to have respondent's parental rights terminated under § 51(6) and at the same time argue that respondent does not have standing to oppose termination under the same section.

B
Having concluded that the probate court erred in its interpretation of § 51(6), we now address whether this error requires reversal of the order terminating respondent's parental rights. We conclude that it does not because the probate court's factual findings establish that the requirements of § 51(6)(a) and (b) were both met.
A petitioner in an adoption proceeding must prove by clear and convincing evidence that termination of parental rights is warranted. This Court reviews the probate court's findings of fact under the clearly erroneous standard. A finding is clearly erroneous if, although there is evidence to support it, the reviewing court is left with a definite and firm conviction that a mistake was made. In re Simon, 171 Mich.App. 443, 448-449, 431 N.W.2d 71 (1988).
In order to terminate parental rights under § 51(6), the requirements of subsections a and b must both be satisfied. In Colon, this Court held that subsection a addresses two different situations: (1) where a parent, when able to do so, fails or neglects to provide regular and substantial support, and (2) where a support order has been issued and the parent fails to substantially comply with it. A parent who seeks to terminate the parental rights of the other parent, against whom there is already a support order, need prove only a substantial failure to comply with the support order for two years before the filing of the petition. The petitioning parent is not additionally required to prove the other parent's ability to comply with the support order because the ability to pay has already been factored into the order. Colon, supra at 809-812, 377 N.W.2d 321.
*260 As an initial matter, we reject respondent's reading of Halbert. Respondent interprets Halbert as precluding the admission or consideration of any evidence not relating to the two-year period immediately preceding the filing of the petition.[2] We find, however, that neither the language of § 51(6) nor Halbert supports such an interpretation. On the contrary, both § 51(6)(a) and (b) describe the relevant statutory period as "2 years or more" (emphasis added). Inclusion of the words "or more" indicates a legislative intent that circumstances beyond the applicable two-year statutory period may be considered. Furthermore, the question decided in Halbert was the commencement date for the statutory period, not whether events occurring outside the two-year period may be considered. Indeed, in construing § 51(6), the Halbert panel stated:
A bare reading of the statute reveals that the two-year statutory period must commence on the filing date of the petition and extend backwards from that date for a period of two years or more. Accordingly, we determine that the statute is satisfied and a petition for termination may be granted where the grounds for termination have been shown to exist for at least two years immediately preceding the filing of the termination petition. [Halbert, supra at 612, 552 N.W.2d 528 (emphasis added).]
In the present case, a support order was entered on October 7, 1985. Therefore, it is only necessary to determine whether respondent had substantially complied with the support order for a period of two years or more before the filing of the petition. Respondent contends that the support order was not violated because it provides that he was not required to pay child support unless petitioner became a recipient of public assistance, and the evidence revealed that this did not occur after the order was entered. However, the order also states that respondent was required to pay confinement expenses of $862.21 and blood-testing fees of $395, as well as Crystal's medical, hospital, dental, optical, and pharmaceutical expenses. At the hearing, petitioner testified, and respondent conceded, that he never paid the confinement expenses or the blood-testing fees and likewise had not paid for any of the child's medical expenses. Consistent with this testimony, the probate court found that respondent "never paid so much as one penny on the Support Order at any time." Thus, because it was established that a support order had been entered with which respondent had failed to substantially comply, the requirements of § 51(6)(a) were satisfied.
Under § 51(6)(b), petitioner was required to prove that respondent, "having the ability to visit, contact, or communicate with the child, has regularly and substantially failed or neglected to do so for a period of 2 years or more before the filing of the petition." Respondent contends that, because of his incarceration, he did not have the ability to visit Crystal during the two-year period immediately preceding the filing of the petition, and therefore his parental rights cannot be terminated. However, the subsection encompasses the ability to "visit, contact, or communicate." The term "or" is generally construed as referring to an alternative or choice between two or more things. Hofmann v. Auto Club Ins. Ass'n., 211 Mich.App. 55, 69, 535 N.W.2d 529 (1995). Because the statute uses the word "or," petitioner was not required to prove that respondent had the ability to perform all three acts. Rather, petitioner merely had to prove that respondent had the ability to perform any one of the acts and substantially failed or neglected to do so for two or more years preceding the filing of the petition.
Respondent testified that he was able to send letters from prison and, in fact, claimed that he had regularly sent letters, cards, and gifts to Crystal. Thus, it was established that respondent had the ability to communicate with the child. The factual issue whether respondent actually had communicated with Crystal was disputed. Although respondent testified that he sent letters, cards, and gifts to Crystal, both petitioner and Crystal herself testified that they had never *261 received anything from respondent. The probate court resolved this factual dispute against respondent.
Respondent contends that the probate court clearly erred because disbursement authorization records from the Department of Corrections will verify that items were sent. However, contrary to respondent's assertion in his appellate brief, he was not precluded from producing such records, even after the hearing.[3] Despite being given the opportunity to provide such records, respondent produced only a single record that something was sent to Crystal on March 2, 1996. This lone instance does not meet the requirement of regular and substantial communication within the meaning of § 51(6)(b). Thus, the probate court's findings establish that the requirements of subsection b were satisfied.
In sum, although the probate court erred in construing § 51(6) as not requiring consideration of the two-year period immediately preceding the filing of the petition, because its factual findings establish that the requirements of subsections a and b were both met, the error was harmless.

II
Respondent next argues that the probate court erred in considering evidence relating to the best interests of the child. Respondent contends that the plain language of M.C.L. § 710.51(6); M.S.A. § 27.3178(551)(6) does not allow the court to consider the best interests of the child.
A probate court's decision to admit evidence at a termination hearing is reviewed for an abuse of discretion. In re Vasquez, 199 Mich.App. 44, 50-51, 501 N.W.2d 231 (1993). We find no abuse of discretion. Section 51(6) states that the probate court may issue an order terminating the rights of the parent if the requirements of subsections a and b are both met. Thus, the statute is permissive and not mandatory. Colon, supra at 812, 377 N.W.2d 321. Because the probate court has discretion, it was not error for it to consider the best interests of the child. Moreover, because the Legislature set forth in the Adoption Code the criteria to be evaluated in determining the best interests of the adoptee, see M.C.L. § 710.22(f); M.S.A. § 27.3178(555.22)(f), we think it unlikely that the probate court is prohibited from considering such evidence when ruling on a petition filed pursuant to § 51(6).

III
In his final issue, respondent contests several of the probate court's factual findings. First, respondent contends that the probate court clearly erred in finding that he has sent petitioner a letter that began, "Dear Bitch, I hate you!" Respondent argues that he denied writing the letter and, consequently, it was never admitted into evidence. However, we find the error, if any, to be harmless because the letter was not material to any of the relevant statutory factors under § 51(6).
Respondent next argues that the probate court clearly erred in finding that respondent's sole interest was in causing petitioner grief and the incurrence of extensive legal expenses. However, given the contents of the letter respondent admitted writing to petitioner's mother, we do not find the probate court's conclusion to be clearly erroneous.
Respondent also asserts that the probate court clearly erred in finding that he *262 did not visit Crystal during a twenty-one-month period commencing in 1990. Respondent claims that this finding is clearly erroneous because he testified that he did visit Crystal during this period. Because both petitioner and Paula Klimas testified that respondent saw Crystal once in 1991, we conclude that the probate court did err. However, because this factual dispute concerns a single visit, which is insufficient to establish regular and substantial visitation, we find the error to be harmless.
Next, respondent argues that the probate court's finding that respondent's visits were not for the purpose of seeing Crystal, but rather were attempts to obtain sex from petitioner, is clearly erroneous because it is based on testimony that was ruled inadmissible. After reviewing the transcript, we conclude that respondent is incorrect. Although respondent's objection to an initial question regarding this subject was sustained, the following colloquy then occurred without objection:

Q. All right. Did Mr. Sienkiewicz actually spend time with the infant or did he spend the visitation time with you?

A. With me.
* * * * * *

Q. Did he ask you [for] or demand anything?

A. Yes, he did.

Q. What did he demand?

A. He was trying to fix our relationship and he was trying to have me engage in sex with him and things like that. He was not there to see my daughter, he was using her to try to get to me.
In light of this testimony, we cannot conclude that the probate court clearly erred in finding that respondent's visits to Crystal were merely excuses to obtain sex from petitioner.
Finally, respondent challenges the probate court's finding that petitioner broke off her relationship with respondent because of the threats and violence. However, at the hearing, petitioner testified that respondent threatened to kill her and then commit suicide afterwards, that he threatened to take Crystal away, that on one occasion her attempt to get him to leave resulted in a physical altercation, and that he once struck her on the head with a bottle. In view of this testimony, the probate court's finding is not clearly erroneous.
Affirmed.
NOTES
[*]  Circuit judge, sitting on the Court of Appeals by assignment.
[1]  Section 39(2) provides:

If the putative father has established a custodial relationship with the child or has provided support or care for the mother during pregnancy or for either mother or child after the child's birth during the 90 days before notice of the hearing was served upon him, the rights of the putative father shall not be terminated except by proceedings in accordance with section 51(6) of this chapter or section 2 of chapter XIIA. [M.C.L. § 710.39(2); M.S.A. § 27.3178(555.39(2).]
[2]  Unlike this case, the probate court in Halbert rendered a finding that the statutory grounds for termination had not been established if the two-year period immediately preceding the filing of the petition were considered. Halbert, supra at 609-610, 552 N.W.2d 528.
[3]  The transcript of the hearing includes the following passage:

[Respondent's attorney]: Your Honor, would the Court like me to, since there was testimony as to these receipts and of letters and gifts being sentI believe I can obtain that from the Department of Corrections if I request those.
[Petitioner's attorney]: I would object. They had their opportunity in the hearings, he rested.
[Respondent's attorney]: Your Honor, I'm just asking. If we're going to cross-examine as to why they wouldn't let him bring them, if the Court wants them I'll get them, if it doesn't I won't. I'm just asking the Court if they'd [sic] like to see them?
The Court: You bring them and also I want someone to run a lien on him. You get his social security number, officer, and anything want to run a lien on him as to [whether] what he said on the stand was or was not true, I don't know. I'd like to verify that.
