Ruling on a father giving wealth to his children and heirs whilst he is still alive

He gave his infant grandson a car as a gift, but he did not give anything to his other grandchildren

He gave one of his wives a house with the agreement of his children from his other wife; after he died, they objected. Is the gift valid or is it part of the estate?

His father gives him money for his university expenses, then there is some extra money left over; is it permissible for him to take it?

Is it permissible for him to accept membership in a Housing Society, which will enable him to get a flat for a cheap price?

His father wants to take back his gift after he was successful in doing business with it

His grandfather divided his wealth between his male children and deprived the females; what should the heirs do?

Ruling on the grandfather showing preference to some of his grandchildren in gift giving

He does not have any children and he wants to give his wealth to his wife and his brother’s daughter and donate the rest to charity

Is it permissible for her to accept gifts from the mothers of children whom she teaches in their homes?