" 'A party seeking to modify an existing custody arrangement must demonstrate a change in circumstances sufficient to warrant an inquiry into whether a change in custody is in the best interests of the child[ ]'" (Matter of Myers v Myers, 192 A.D.3d 1681, 1682 [4th Dept 2021]; see Matter of Heinsler v Sero, 177 A.D.3d 1316, 1316 [4th Dept 2019]; Matter of Cole v Nofri, 107 A.D.3d 1510, 1511 [4th Dept 2013], appeal dismissed 22 N.Y.3d 1083 [2014]). "Although, as a general rule, the custody determination of the trial court is entitled to great deference (see Eschbach v Eschbach, 56 N.Y.2d 167, 173-174 [1982]), '[s]uch deference is not warranted... where the custody determination lacks a sound and substantial basis in the record'" (Cole, 107 A.D.3d at 1511).
Family Court granted the motion and dismissed the first and second petitions, thereby implicitly dismissing the amended petition, and the mother now appeals, [1, 2] " ‘A party seeking to modify an existing custody arrangement must demonstrate a change in circumstances sufficient to warrant an inquiry into whether a change in custody is in the best interests of the child[ ]’ " (Matter of Myers v. Myers, 192 A.D.3d 1681, 1682, 141 N.Y.S.3d 393 [4th Dept. 2021]; see Matter of Heinsler v. Sero, 177 A.D.3d 1316, 1316, 114 N.Y.S.3d 536 [4th Dept. 2019]; Matter of Cole v. Npfri, 107 A.D.3d 1510, 1511, 967 N.Y.S.2d 552 [4th Dept. 2013], appeal dismissed 22 N.Y.3d 1083, 981 N.Y.S.2d 666, 4 N.E.3d 967 [2014]). "Although, as a general rule, the custody determination of the trial court is entitled to great deference (see Eschbach v. Eschbach, 56 N.Y.2d 167, 173-174, 451 N.Y.S.2d 658, 436 N.E.2d 1260 [1982]), ‘[s]uch deference is not warranted .. where the custody determination lacks a sound and substantial basis in the record’ " (Cole, 107 A.D.3d at 1511, 967 N.Y.S.2d 552).