The Hindu Adoptions and Maintenance Act,1956
14. Determination of adoptive mother in certain cases.-
(1) Where Hindu who has a wife living adopts a child, she shall be deemed to be the adoptive mother.
(2) Where an adoption has been made with the consent of more than one wife, the senior most in marriage among them shall be deemed to be the adoptive mother and the others to be step-mothers.
(3) Where a widower or a bachelor adopts a child, any wife whom he subsequently marries shall be deemed to be the step-mother of the adopted child.
(4) Where a widow or an unmarried woman adopts a child, any husband whom she marries subsequently shall be deemed to be the step-father of the adopted child.