1 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. 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 Question: What is the stance of Islam in regards to adopting children and if a child is with the family from his or her early days and develops a bond, do the laws of Mahram and Non-Mahram still have to be observed?
Answer: Adoption in the sense of claiming a child as your own son or daughter and getting an ID card for him or her in your name is not permissible. However, there is no Ishkaal (objection) in taking care of a child, raising him or her and showing love and care which is rather good but the child's lineage has to be preserved. In addition, developing a bond does not cause Mahramiyat. The child should be informed about it and if he cannot inform the child, he should record it somewhere or ask someone to bear witness that he/she is not his child.