Interference in my father's property by first cousins

Dear sir, My grandfather was having 1000 Gaj land (home ist floor & dairy business ground floor). My father's eldest and youngest brother are no more today and property dispute is going on from last 2 months..and my taya's kids and wife does not want to give equal property to my chacha's son (reason is- my chacha didn't do any work when he was alive)...and they are telling my father and my brother to be with them and will divide the property (400:400:200) respectively...200gaj only for chacha's kids...my father and brother are not getting agreed to it because it is injustice with my chacha's kids...and now they want to divide the land in 500:250:250 Gaj respectively. We are having an Idea mobile tower and by legal documents, it is my father's property and we are having proofs (my taya's kids don't know about proofs) but they are saying that land is ours and it is coming under their 500 Gaj...but they are claiming that 121 Gaj land in their 500 Gaj...and today they called my father to sign over a document without even detailing him about it...we have strictly told our father to not sign on any such kind of documents... I know,, taking this case to court will stretch only our time and so much money would be spent which we don't afford...because money power is in my taya's elder son's hand... Please please help me about what can be done in this matter. P.s- it is a joint family and combined business it is till today...and even though combined business it is...my taya's kids have worth 1 crore land property (money from combined business) and they are not willing to give even a single piece of land to us. And having so much property...they want 500 Gaj also from our inherit 1000gaj property...