Is it forbidden to agree to a father’s relinquishment of his property to his male children without the knowledge of one of the sons, and to deprive the daughters of their inheritance at the request of the eldest brother?

The father's relinquishment of his wealth to his children is considered a gift, and the Prophet, peace and blessings be upon him, commanded equality among children in this regard, based on the hadith of Nu'man ibn Bashir: "Did you do this with all your children?" He said: "No." He said: "Then fear Allah and be just among your children." Therefore, it is forbidden to agree to injustice in a gift, and the ruling must be explained to the father, and he should be advised to be just. If he does not respond, then the brothers must be urged to give their sisters their rights, otherwise, the son should leave for them from his share what is not rightfully his.