What is the Islamic ruling regarding the problem of the youngest daughter who feels inferior and sad because she did not receive a share from her father like her sisters, and is she entitled to hold on to the official contract that her mother secretly wrote for her for the family apartment as compensation, especially after the dispute that arose between her and her mother, and the desire of the other siblings to inherit it, given the father's approval to give her the apartment?

A father must be just among his children in giving gifts and presents. Your father is excused for not helping you with marriage due to his poverty. The apartment your mother registered in your name is not considered a complete gift because you have not taken possession of it, and a gift cannot be conditional or for a future date. A mother has the right to revoke her gift to her child, and if the mother never originally took possession of the apartment, it still belongs to the father. You must return the contract to your mother, and honoring your parents is paramount.