Does the apartment that the father bequeathed to his widow, who is not the mother of the heirs, become part of the inheritance or is it given to her?

The answer is summarized in two points:

Firstly: If the heirs know that the apartment belongs to their stepmother, they must enable her to possess it, and the apartment is not considered an inheritance.

Secondly: If the apartment belonged to the father and he bequeathed it to his wife, then this is a bequest to an heir which is not effective unless approved by the adult, mature heirs. If they do not approve, the apartment is divided according to Islamic law among all the heirs.