Need information on division of property

My father died in 1997. He willed all his self earned property to my mother through notorised & attested will. My mother has willed all her property including all moveable and immoveable property to me and my brother half-half through a registered will before she died. My two elder sisters are now also demanding 1/4th of the property each. What should me and my brother do? We have spent all the liquid cash on mothers illness. They are demanding 1/4th share in fathers liquid cash also which he left behind. We have a small house which we want to sell and divide between two brothers. Sisters are non-compromising type. I am a hindu. Can we sell the house after it is transferred in Nagar Nigam in our name? Can the buyer ask for more compensation (whatever we have received + compensation) if the sisters go to court later on?