Is it permissible to divide the inheritance equally between the son and the daughter in the presence of the wife who is not their mother? And does her remarrying affect her right to the inheritance?

The will of the deceased stipulating that the son should receive a share equal to that of the female is not valid. The wife is entitled to her share of the inheritance even if she remarries before receiving it. For one who passed away leaving behind a wife, a son, and a daughter, and no other heirs, the wife receives one-eighth due to the existence of a lineal descendant, as Allah Almighty says: "But if you have a child, then for them [the wives] is one eighth of what you leave, after any bequest you [may have] made or debt." The remainder goes to the son and daughter by way of ta'seeb (agnatic inheritance), with the male receiving a share equal to that of two females, as Allah Almighty says: "Allah instructs you concerning your children: for the male, what is equal to the share of two females." Thus, the inheritance is divided into twenty-four shares: the wife receives three shares, the son fourteen shares, and the daughter seven shares. The matter of inheritances must be referred to the Sharia courts for investigation to secure the interests of both the living and the deceased.