I am divorced from ex . Who has been a father figure to my oldest daughter for 15 1/2 years . She is 16 (17 in June of 07) . If she decides to move in with him . Can he sue me for C/S ? He is NOT the bio dad . And he does NOT have legal custody of her at this time . Can he sue me for C/S , or will the bio dad have to be brought into this matter ?