How can one marry, Islamically and legally, an adult orphan young man who has no identity, for the purpose of helping and caring for him?

The legal method of marriage is achieved by observing the conditions of validity, the most important of which are: the guardian (wali) and witnesses. Whoever wishes to marry you can propose to your guardian for engagement, then complete the marriage with a legal contract. Legal impediments should be observed to avoid embarrassment, for the Prophet, peace and blessings be upon him, said: "Beware of that for which an excuse must be made." A residency permit is not a legal impediment to marriage, but violating its regulations may lead to embarrassment.