Memorandum:
Family Court did not abuse its discretion in granting respondent's cross petition seeking sole custody of the parties' child. Pursuant to a 1993 divorce decree, incorporating but not merging an agreement of the parties, the parties had joint custody of their child, with primary physical placement of the child with petitioner. "[A] long-term custodial arrangement established by agreement should prevail `unless it is demonstrated that the custodial parent is unfit or perhaps less fit'" ( Fox v. Fox, 177 A.D.2d 209, 211; see also, Matter of Ammann v. Ammann, 209 A.D.2d 1032, 1033). The court properly determined, inter alia, that, because of the efforts of petitioner to exclude respondent from the child's life and her attempts to sabotage respondent's positive relationship with the child, the best interests of the child are served by transferring custody to respondent ( see generally, Friederwitzer v. Friederwitzer, 55 N.Y.2d 89, 95). Moreover, because of petitioner's hostility toward respondent, the parties are unable to act together for the benefit of their child ( see, Matter of Buffy E. v. Lance C., 227 A.D.2d 903, 904).