If your grandfather insists on giving the house to your father and his ex-wife's children: that is, infringing on your property ownership, you can sue your grandfather in court.
2. But if your parents' house in Area A belongs to you, but it has not been transferred to your name, that is to say, the property ownership certificate of the house in Area A is still the name of your parents or your grandfather: if you are in trouble, your father or your grandfather has the right to handle this house.
3. "What can I do if I don't give them a house and I can't get the demolition fee?" ：
(1) As long as your name is on the property ownership certificate of Area A; Don't worry, take the real estate license in your hand, let the demolition office tell you that you are the owner (the demolition office will also check), and then you can handle all the demolition matters yourself: just do it.
(2) If your name is not on the property ownership certificate: your parents say that the house is yours, you must ask your parents to help you transfer the property ownership certificate to your name before the demolition starts.
(3) Wrong, you are under 18 years old: you need a guardian to handle the demolition. Ask your father or mother to help you, but you must always pay attention to the progress.