Is it unlawful for a father to gift his only daughter an apartment he owns during his lifetime, and is she entitled to inherit the remainder of his estate after his death, and how can he be convinced of this without misunderstanding?

Your father is permitted to grant you whatever he wishes during his lifetime and while he is in good health. If you take possession of what he has granted you, it becomes your property, and you will inherit whatever remains of his estate after his death. A gift completed while the giver is in good health is valid and permissible, even if it is intended to disinherit other heirs. The method of convincing your father to grant you the apartment varies with individuals and situations, and you are most knowledgeable about the appropriate approaches for your father.