The Women - 4:6
Test the orphans when they reach the age of marriage. If you see maturity in them, give them their property. Do not eat their wealth in extravagance and haste, lest they grow up. Let the rich give up (the wages of his efforts to protect the property). Let the poor spend an appropriate amount. Return their property to them in the presence of witnesses. Allah is sufficient as the Reckoner.
When orphans become family members:
The Coalition/33:4
Allah has not put two hearts in any man. He has not made your wives your mothers, whom you forbade yourselves by likening them to your mothers, nor has He made your adopted children your own children. All this is but the words of your mouths. Allah speaks the truth and He guides.
The Coalition/33:5
Call them in a way that does not cut them off from their natural fathers. This is more right in the sight of Allah. If you do not know their fathers, then they are your brothers in religion and members of your family. There is no responsibility on you for what you do by mistake, except what you do intentionally. Allah is Forgiving, Merciful.