Is raising a foundling and her mixing with a family that is not related to her, taking her salary, and her family problems considered unlawful (haram)? And what is the concept of a foundling in Islamic law, and how should she be dealt with?

A foundling is a child of unknown parentage whose parents are not known, and they may or may not be born out of wedlock. Sponsoring them is permissible and rewarded, and it is no less meritorious than sponsoring an orphan; in fact, it may be greater due to their severe need. A person of unknown parentage is considered an orphan due to the loss of their parents, and sponsoring them entitles the sponsor to the reward associated with sponsoring an orphan, in accordance with the general saying of the Prophet, peace and blessings be upon him: "I and the sponsor of an orphan will be in Paradise like this," and he indicated with his index and middle fingers. If there is no one to raise the girl, sponsoring her brings a great reward. It is not necessary for the foundling to be born out of wedlock, and even if they were, they are not to blame for it. The girl's salary is not unlawful as long as it comes from a permissible work. What is unlawful is taking more than her needs without her consent when she is an adult of sound mind. The problems that may afflict the sponsor are not due to the ill-omen of sponsoring a foundling, but rather a trial from Allah to test their patience.