House property which may get disputed due to will

We are two brothers and three sisters, We all are married,We two brothers live in a house with our parents The house in which we live is bought by my father from his hard earned money,and he is owner of house. My father made a registered will in which he has given house equally to both of his sons(me and my brother). Nothing to sisters. So, my question is that if in future any of my sisters demanded their share from the house, what will we do?? If the sisters acted legally and ask their share from this ancestral property of their father then what ll we do? Do we have to give share out of this house. My father has no other property, except this house in which we live together. Please reply. Regards RK