Are all the children of a suckling woman considered brothers to the strange child whom their mother had breastfed, or just to the one who had suckled with him?
All the children of the woman who had suckled a strange child are considered his/her brothers and sisters.
Is it permissible for a father to disinherit his disobedient, alcohol consuming son and his daughter who had fled home and never returned?
All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
It is permissible to give heirs some money because of their being extra obedient or needy. As far as inheritance is concerned, it is to be divided after one`s death, so it had better be left to the court itself. And Allah The Almighty Knows Best.
Is it permissible for the guardian to give Sadaqa (voluntary charity) from the money of the orphans?
It is impermissible for the guardian to donate from the money of the orphans because he is entrusted with the safekeeping of that money, and is prohibited from donating it.
Is it permissible to make up for the missed fasts of the deceased?
A deceased`s missed fasts should be made up for by his/her guardian. It is also permissible to make up for the missed fasts of a deceased relative, and to pay a ransom in expiation for the latter`s missed fasts, which is feeding a needy person for every missed day. However, the guardian`s permission need to be sought by the non-relatives of the dead to fast on his behalf. And Allah Knows Best.