A woman says she owns a piece of land that she inherited from her father. After two of her children grew up and started working, they collaborated with their father and mother according to their abilities and built a large apartment for their parents and younger siblings, measuring (155) square meters. Each of them also built a small apartment for their parents, measuring (70) square meters. After a few years, the third child grew up, worked, and built a large apartment above his parents' apartment, measuring (130) square meters. There are still vacant areas of land around the building, and the mother wants to register each apartment in the name of its respective owner. Now, the eldest son wants to build on the vacant land and wishes to construct a (260) cubic meter duplex, and he plans to give his apartment to one of his siblings in exchange for installments. Is it permissible for the mother to give him larger areas to build on compared to his siblings, especially since he still has three younger siblings?