Appellant appeals from judgment of sentence imposed following his conviction of several offenses relating to his sexual abuse of his granddaughter while he was baby-sitting her for her parents. We affirm.
The relevant facts and procedural history have been accurately set forth in the trial court opinion. They will be *234repeated here only as necessary to address the issues raised on appeal.
On appeal, appellant contends the evidence is insufficient to establish that the crimes occurred within the applicable statute of limitations period; counsel was ineffective in failing to seek dismissal of one of the charges on statute of limitations grounds; one of appellant’s other granddaughter’s was improperly permitted to testify in rebuttal regarding similar but uncharged bad acts expressly denied by appellant during cross-examination; and, the trial court erred in failing to give a requested instruction on the relevance of the absence of a prompt complaint by the child victim. We find no merit in the contentions.
Appellant’s first statute of limitations challenge is plainly without merit. Review of the record reveals that the trial court specifically instructed the jury that in order to convict appellant, they had to decide that the offense charged occurred between March 21, 1986 and September 4, 1986. (See N.T. 9/15/88 at 382). The victim testified to a pattern of sexual abuse occurring between January 1983 and September 4, 1986. (See N.T. 9/12/88 at 22-46). This evidence was sufficient to sustain the conviction. See Commonwealth v. Bethlehem, 391 Pa.Super. 162, 171, 570 A.2d 563, 568 (1989); Commonwealth v. Allem, 367 Pa.Super. 173, 181-82 nn. 2-3, 532 A.2d 845, 849 & nn. 2-3 (1987); Commonwealth v. Niemetz, 282 Pa.Super. 431, 422 A.2d 1369 (1980). The existence of evidence of a continuing course of similar sexual abuse throughout a period which extends into the applicable limitations period, coupled with an unequivocal instruction as to the parameters of the limitations period, distinguishes this case in factually material respects from the scenario presented in Commonwealth v. Thek, 376 Pa.Super. 390, 402-03, 546 A.2d 83, 90 (1988), wherein a superficially similar claim was found to be meritorious. We reject appellant’s first claim.
Appellant’s related claim of ineffective assistance of counsel for failure to pursue a pre-trial motion to quash on *235statute of limitations grounds is likewise without merit. Assuming, arguendo, that a claim could have been presented pre-trial, based upon the lack of specificity with which the charges were drawn, nonetheless, there was no prejudice to appellant in this case.
While appellant vigorously denied the charges and attempted to discredit the victim’s testimony in several respects, he freely conceded that he had acted in loco parentis for the victim’s absent parents at the times when the victim testified that the abuse occurred. We conclude that as an adult baby-sitter for absent parents, appellant was acting as “a person responsible for the child’s welfare” within the meaning of the phrase in 42 Pa.C.S.A. § 5554(3) which provides in pertinent part:
§ 5554. Tolling of statute
... the period of limitation does not run during any time when:
(3) a child is under 18 years of age, where the crime involves injuries to the person of the child caused by the wrongful act, or neglect, or unlawful violence, or negligence of [ ...] a person responsible for the child’s welfare.
(Emphasis added).
In Commonwealth v. Bethlehem, supra, this Court stated:
We do not believe that in the context of this statute the phrase, “person responsible for the child’s welfare,” was intended by the legislature to apply to an uncle visiting the victim’s parents’ home. Without precluding application of this portion of the tolling provision to such a relative under different circumstances, at least when, as here, the parents were at home and in the next room when the sexual assault occurred, it was the parents and not the visiting relative who remained the “person(s) responsible for the child’s welfare” within the meaning of the provision in question. We construe the provision to apply to persons under whose permanent or temporary *236custody and control the parent(s) or legal guardian(s) have placed a child, in other words, those who stand in loco parentis to the child. See 1 Pa.C.S.A. § 1903(b). The Commonwealth made no showing of such responsibility being vested in Bethlehem at the time of the assaults. Hence, we must conclude that this portion of the tolling statute could not properly be applied to the circumstances of this case.
570 A.2d at 566. (Emphasis added). Here, the babysitting grandfather, unlike the visiting uncle, had been placed temporarily in loco parentis by the absent parents when the assaults occurred. Hence, in accordance with the reasoning set forth in Bethlehem, we conclude that appellant was “a person responsible for the child’s welfare” within the meaning of 42 Pa.C.S.A. § 5554(3).
Appellant’s status as a “person responsible for the child’s welfare” at the time of the offense was committed triggers the tolling of the applicable statute of limitations period from the effective date of the provision through the victim’s eighteenth birthday (a date after the filing of the charges in this matter). Thus, the proper cut-off date for the applicable limitations period was September 8, 1983, rather than March 21, 1986. See Commonwealth v. Thek, supra, 546 A.2d at 89 & nn. 8-9.
Had the trial court been called upon to determine the precise cut-off date of the limitations period, the jury properly could have been informed that September 8, 1983, rather than March 21, 1986, was the appropriate limitations cut-off date. Thus, there was an objectively reasonable basis for competent counsel to avoid that subject. More importantly, appellant was advantaged, rather than prejudiced by counsel’s avoidance of this issue pre-trial, in light of the eventual issuance of an overly favorable instruction to the jury on this issue by the trial court.
It is, of course, entirely irrelevant whether counsel’s conduct was actually deft, or merely fortuitous. Counsel cannot be found ineffective for doing the right things for wrong reasons, or for no apparent reasons. There was, in *237fact, an objectively reasonable basis for competent counsel to pursue the precise course of conduct challenged, and there was no actual prejudice. Hence, the second claim must fail. See Commonwealth v. Petras, 368 Pa.Super. 372, 534 A.2d 483 (1987).
Appellant next contends that the trial court improperly permitted the Commonwealth to rebut appellant’s testimony on cross-examination that he had never shown his x-rated video tapes to any of his grandchildren, with testimony of another grandchild that he had shown his x-rated movies to her. We find no merit in the contention.
Evidence of prior bad acts is admissible in rebuttal to dispel false inferences raised by the defendant or the defendant’s witnesses. See Commonwealth v. Saxton, 516 Pa. 196, 532 A.2d 352 (1987); Commonwealth v. Trignani, 334 Pa.Super. 526, 483 A.2d 862 (1984). The fact that the false inferences may have arisen through testimony on cross-examination does not alter the analysis. See Commonwealth v. Smith, 490 Pa. 380, 390, 416 A.2d 986, 990-91 (1980); Commonwealth v. Hickman, 453 Pa. 427, 432, 309 A.2d 564, 567 (1973). Appellant plainly “opened the door” to the rebuttal evidence with his answer on cross-examination that he never exhibited his x-rated video tapes to any of his grandchildren.
Moreover, the rebuttal evidence, rather than indicating an isolated and unrelated prior bad act, indicated an event which formed a part of a pattern of sexual abuse of the young female relatives placed in appellant’s care by the children’s unsuspecting parents. Such evidence was relevant to show design, and was highly corroborative of the victim’s testimony regarding the continuing and escalating course of sexual abuse committed. See Commonwealth v. Claypool, 508 Pa. 198, 204, 495 A.2d 176, 181 (1985) (Hutchinson, J., concurring); Commonwealth v. Kline, 361 Pa. 434, 65 A.2d 348 (1949); Commonwealth v. Dunkle, 385 Pa.Super. 317, 335, 561 A.2d 5, 14 (1989) (Kelly, J., dissent*238ing) (collecting cases and authorities).1 We note that the rebuttal evidence here involved identical conduct (exhibition of x-rated tapes during baby-sitting) toward another granddaughter of similar age after the period which the victim testified the continuous course of escalating abuse occurred and was virtually indistinguishable from the similarly corroborative evidence of the victim herself regarding similar acts occurring outside the limitations period.
Finally, appellant claims the trial court erred in refusing to instruct the jury specifically that the absence of a prompt complaint by the victim must be considered in determining her credibility. We find no merit in this contention.
Appellant relies principally on Commonwealth v. Lane, 521 Pa. 390, 555 A.2d 1246 (1989). Reliance upon that case for the proposition that the jury instruction requested was required, was misplaced.
In Lane, our Supreme Court held that a new trial was required when a juror was improperly excluded for cause based on answers on voir dire that the prospective juror would have difficulty believing that an eight year-old raped by an acquaintance who lived with her mother’s friend would wait as long as had been indicated to report the offense, if the offense had occurred as alleged. 555 A.2d at 1248-49. Our Supreme Court reaffirmed that the defendant was entitled to present, and the jury was entitled to consider, evidence of the absence of a prompt complaint by the victim. 555 A.2d at 1250-51.2 Nowhere in Lane, how*239ever, is there the faintest suggestion that the jury instruction requested here was required.
The form and content of jury instructions is left to the sound discretion of the trial court. Commonwealth v. Alvin, 357 Pa.Super. 509, 519, 516 A.2d 376, 381 (1986). The charge given here adequately covered the general issue of credibility. To have given the charge requested would have given undue weight to a single factor in the jury’s complex credibility analysis. Consequently, we conclude that the trial court acted within its discretion in rejecting the proposed instruction.
Based upon the foregoing, Judgment of Sentence is Affirmed.
DEL SOLE, J., filed a dissenting opinion.. In Commonwealth v. Shively, 492 Pa. 411, 424 A.2d 1257 (1981), there is language purporting to expressly overrule Commonwealth v. Kline in this respect. 424 A.2d at 1259-60. The opinion was joined by one justice, two justices concurred in the result only, and two justices dissented. Consequently, the lead opinion of the plurality had no precedential authority and Commonwealth v. Kline must be deemed to remain precedential. No subsequent decision by our Supreme Court has embraced the dictum of the lead opinion of the Shively ■ plurality.
. We note that in Lane, our Supreme Court also stated, "the inference of insincerity is only justified where the facts of the case fail to disclose a reasonable explanation for the challenged time lapse prior *239to the complaint.” 555 A.2d at 1250; cf. Commonwealth v. Willis, 380 Pa.Super. 555, 574-75, 552 A.2d 682, 691-92 & n. 5 (1989) (noting the limited relevance of the absence of a prompt complaint generally, and especially in cases involving child victims of non-violent intrafamilial sexual abuse; collecting authorities); Commonwealth v. Stohr, 361 Pa.Super. 293, 311-12, 522 A.2d 589, 598-99 & n. 4 (1987) (Kelly, J., concurring; McEwen, J., joins) (same). The absence of a prompt complaint in non-violent child sexual abuse cases is common. See e.g. Commonwealth v. Bethlehem, supra, 570 A.2d at 566 n. 2; Commonwealth v. Slocum, 384 Pa.Super. 428, 436 & n. 4, 559 A.2d 50, 54 & n. 4 (1989) (noting authorities).