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?

Her father paid her university fees, then the university returned the fees as a prize to her; does her father have the right to take them?

Is it permissible for a man to put a house in his ex-wife’s name?

Are gifts for weddings and other occasions like a debt that must be given to the giver on a subsequent special occasion?

He died and left behind a son and six daughters

He gave more to the males than to the females then he died

Is it permissible for them to register what the father owns in one of the sons’ names because their father’s wife wants to do that for herself?

Should she return the wedding dress to the fiancé after cancelling the engagement or does she have to return its price?