Conclusion: These two boys are brothers of this girl through their mother, and they may live in the same house, because they are siblings, unless there is the fear of any harm to this Muslim girl in terms of her religious and moral well-being, from these two Christian brothers or from one of them, in which case she should not live with them. But if they are trustworthy and of sound character, then there is nothing wrong with that. See also the answer to question no. 21953. And Allah knows best.

The maternal aunt has a high status in Islam, which is similar to that of the mother. You should show kindness, honour, and uphold ties of kinship with your maternal aunt.

Conclusion: your brother may be your mahram for the purpose of travel if he is trustworthy. We ask Allah, may He be exalted, to guide him. And Allah knows best.

The husband’s brothers and uncles (maternal or paternal) are not Mahrams to the wife. Rather the only ones who are her Mahrams are the husband’s father and grandfather, and the husband’s son and grandsons.

The husband’s grandfather, whether he is the father of his father or his mother, is a Mahram. So there is no blame on you for uncovering your face and hands and so on in front of him.