Memorandum:
Supreme Court denied plaintiff's motion to set aside the opting-out agreement that was incorporated but not merged into the judgment of divorce. We agree that the order was proper but for a different reason. "A party seeking to set aside an agreement must do so by commencement of a plenary action, by affirmative defense or by counterclaim; such relief cannot be obtained on motion" ( Gaines v Gaines, 188 AD2d 1048). Were we to reach the merits of plaintiff's motion, we would affirm for reasons stated in the decision at Supreme Court. (Appeal from Order of Supreme Court, Onondaga County, Stone, J."Set Aside Agreement.)