Is a brother entitled to retract his waiver of part of the inheritance after the agreement on its distribution, if the retraction is due to the disapproval of his full siblings, the ill-treatment by the stepmother and her children, and their failure to enable him to receive his full share?

A voluntary waiver by an adult, mature heir of their share is considered a valid gift from them. This gift does not become binding and irrevocable unless the donee takes possession of the gift before the donor retracts. If the gift is already in the donee's possession, it becomes binding upon offer and acceptance. The renunciant has no right to retract their waiver if the gift has been possessed, and the injustice of the heirs does not justify retracting the waiver; rather, the renunciant has the right to demand their share from them and take them to court.