Family property dispute

Sir, I wish to bring some facts before asking my doubt. Actually, my grand mother (mom's mom), who owned a house property in Chennai, was died in 2015. She has three sons and two daughters (including my mother). One of my uncles, i.e., my grand mother's son and my mother's elder brother, alone is residing in this house along with his family. After demise of my grand mother, my uncles have planned to share this property among themselves and trying to exclude their two sisters. The problem here is we are extremely unaware of the property details as land extent, patta etc. We dont know whether the property document is available or not or it has placed in the bank locker. Using this my maternal uncles are urging to obtain legal heir certificate in their names alone. Besides once they all had threatened my mother and aunt regarding the property dispute during the 1st year remembrance day of my grand mother. Now what I want to know is can we initiate any legal proceedings or criminal action against their cunning attitude and being a women, how my mother and her sister can claim their lawful rights over the property. Can we lodge any police complaint regarding property dispute. Do we need any records to claim the rights over this property. My uncles also refused to sell the property since they should have to give a share to their sisters from the sale proceeds. Is there any way to claim share in case of non sale of property. Kindly help us by giving your valuable legal advice to claim legal share. Please sir.