Question: Are we allowed to adopt children and consider them as our own children?
Answer: It is permissible for a person to adopt a child and taking care of a deserving child is earns the individual reward, but the child is not considered his son or daughter; the child remains a stranger (non-mahram) to him or his wife and he or she does not inherit the person who has adopted him or her.[1] Adoption in the sense to change a child's name and register him in his ID card as his own child is not permissible. It is not permissible to change the child's father name.[2]
1. Ayatollah Seyyed Ali Sistani, Question & Answer, adoption; Ayatollah Seyyed Ali Khamenei, Practical Laws of Islam, Q1007.
2. Ayatollah Seyyed Ali Sistani, Question & Answer, adoption.