Disputes related to ancestral property

Dear Sir/Madam, Greetings of the day. I have a few questions regarding our ancestral property disputes between claimants. The property is nearly 2 bigha in total, an one storey building consisting 4 rooms and a pond measuring about 1 bigha is in between. total property is guraded by wall. Owner was my grandfather.He died 30 years ago without any will deed. he had 3 daughters, 2 sons, I am his grandson from his younger son who ( my father) died 14 years ago. His elder son ( my uncle) is unmarried and lives in USA and relinquished his claim. Only we are (My father and his family) in possession and dwellers in the building for more than 30 years. After My father's death I live with my mother and younger brother. Now, My aunts ( My father's Sisters) want their share and for that they are doing like this:-- 1. One of my aunt somehow managed to steal original legal papers ( Dalil) from this house a few years ago and when we realized & asked her to return she denied. 2. They are not negotiating anything with us and sending outsiders to let us know their versions. 3. They Now want us to vacate the house and sell the total property. As we are financially weaker, it is impossible for us and we don't want to leave this house. 4. Their another plan is to give us the only this 60 years old decayed building and take rest of everything ( land, pond) for them. 5. Farming fish in that pond I somehow earn a few bucks to support my living. Now they are sending promoters to fill up the pond ( which I think is illegal) and sell. 6. As they know we are financially weak, they are threatening to move court for law-suit and forcefully get us out of home. 7. They are inviting many parties to show the land pretending to be the owner as they have acquired the legal papers( Dalil) and it is also heard that they are projecting us to the parties that we are tenants and hence completely ignoring us to negotiate. With this situation in hand if you please guide me a few things about that and let me know the actual rules and proceedings, I shall be grateful. Thanking You- Aniruddha Nath Address - Kaugachi, Vivekananda nagar, P.O. Shyamnagar 24pgs (n) westbengal