Is a brother entitled to demand the return of money he spent on his sisters on the grounds that it is a debt, or is he obligated to spend on his family?

The money the brother gave to his parents is either a gift, which cannot be retracted, or a loan, which can be demanded. The maintenance of poor parents is obligatory upon a wealthy son. However, if the father has sufficient money, then maintenance is not obligatory. If the money was a gift, the father is not permitted to agree to its return. If the father gave money to his son as a gift, he must be fair by giving the daughters half of what he gave the son, unless the daughters agree to the favoritism. If the father dies without having been fair in his gift, the son must return the money to the estate to be divided among the heirs. As for what the father spent on educating his children or their marriage, it is considered maintenance for which he is not required to be fair, and it cannot be demanded from the inheritance. All that the father left, including lands and other assets, is part of the estate and must be divided according to Islamic law. It is not permissible for the wife or any of the heirs to exclusively take the money deposited in the bank except with the consent of all heirs.