Appellant, whose order of disposition has already been affirmed by this Court ( 29 AD3d 386), moved, pursuant to Family Court Act §§ 315.2 and 355.1, to vacate the order of disposition and dismiss the petition on the ground that, after a separate, subsequent fact-finding hearing, the same Judge who presided over appellant's hearing dismissed the petition against the three juveniles with whom appellant allegedly acted in concert in sexually abusing the victim. While it is generally no defense to a prosecution based on accessorial liability that a co-actor "has not been prosecuted for or convicted of any offense based upon the conduct in question, or has previously been acquitted thereof (Penal Law § 20.05; see also Matter of Khaliek W., 193 AD2d 683, 684), we find, under the facts presented herein, that a substantial change in circumstances exists and that appellant should be granted a new fact-finding hearing at which he would be given the opportunity to elicit impeaching testimony introduced at the other three juveniles' hearing ( see Family Ct Act § 355.1).