Gift deed query

Gift deed is not taxable.. If so.. Brother transfers gift to sister (property - flat) which is in his name. They are asking for money with us 5lakh. As per the gift deed norms there should not be any monetary exchange of money during transaction. If they are asking for money then what is the possible cases they may asked money for.. hoping for the utmost possibility.. as it is given to a builder in Joint venture by him.. and now he wants to gift it to sister..