The only persons required to sign legal documents relinquishing parental rights so that an adoption can occur, are the birth parents of the baby.

The birthfather, the mother’s husband, and the mother are the only parents unless someone else has taken care of the child for a period of 6 months or longer. In that case, the person that has provided for the child might be considered to have some rights about making the decision. Those rights would have to be determined in a court of law.