hindu succession act

This is ancestral property so your sisters right in this property. Thay challenge WILL.

you say the house has been build by you father on the land which he inherited. that mean sthe house is self acquired by you father and the land is ancestral, so this will lead the sisters toi claim their rights as there is a equal rights given to the daughters in the Hindu succession Act. There is no need to cancel the registred will which your father has already done in your favour as you are taking care of them. you can call your sisters and mutually reconcile the matters . By using sugar coated words you can force them to accept a certain sum of money as a gift from your father and then take a declaration from them that in future they are not going to return back with their flase claims ont he house .

You have stated that the land on which your father constructed the house was ancestral property which was divided (partitioned) amongst your father and his brothers. In other words the land was the portion which he got in the  partition and ur father built the house on that protion. If this is the correct p[ostion, then the land ceases to have the character of ancestral property and legally will be regrded as his self acquisition. Consequently, the house also is his self acquired. He thus can dispose of the house by will in whatever manner he decides. Daughters cannot object to his decision to gi ve the house to you solely.