Should the couple give up their adopted daughter in obedience to the husband's parents, especially with fears for her well-being in a non-Muslim family, particularly since the adoption was from an institution that does not disclose her biological parents?

Adopting a girl, raising her, and caring for her without changing her lineage is a righteous and permissible act. However, the girl does not acquire the status of a daughter in terms of lineage and inheritance. If the adopter attributes her lineage to himself, then this adoption is forbidden, and he must reverse it by correcting her name in official documents so that she is not attributed to him and does not inherit from him. He must also repent and seek forgiveness. If the girl's lineage is unknown, she should be attributed to a name that signifies servitude to Allah, such as: "So-and-so, daughter of Abdullah ibn Abdul-Hamid." The son should inform his parents about the ruling on this matter with wisdom and good counsel. He is not obligated to return the girl to the adoption institution due to the danger that poses to her, unless her parents are alive, Muslim, and can be reached without fear for the girl. His parents do not have the right to ask him to abandon her, and he is not obliged to obey them in this regard. Rather, he must explain the ruling to them and deal with them tactfully.