In a consolidated family law appeal, the court overruled its decision in Alison D. v. Virginia M., 77 N.Y.2d 651 (1991), and held that an unmarried partner who lacks a biological or adoptive connection to subject children has standing to seek visitation and custody under Domestic Relations Law section 70 by showing, clearly and convincingly, that the parties agreed to conceive a child and raise the child together.