What is the ruling of Islamic law on a father registering his house in the name of his first wife, fearing demands from his second wife who threatens to seize the house after his death, while ensuring accommodation for the second wife and her children?

It is not permissible for a father to register the house in the wife's name or bequeath it to her to disinherit some heirs, as this is not valid and does not pass except with the consent of the adult heirs, due to the saying of the Prophet, peace and blessings be upon him: "Indeed, Allah has given every rightful person his right, so there is no will for an heir." Also, it is not valid as an "immediate gift" because it lacks justice among children and wives, and due to the saying of the Prophet, peace and blessings be upon him: "Fear Allah and be just among your children."

The correct solution is to follow the law of Allah Almighty, as all properties of the deceased father are considered the property of all heirs, and Allah has undertaken to divide them justly. Therefore, the stepmother or anyone else cannot expel the children from the house.