Cheated by Sisters

I was working in foriegn.The property was owned by my late: (mother and Aunts( her two sisters).There was one more owner for that propperty my late Uncle(mothers brother).There was a case done by my uncles kids and my mother and aunts.Last they got there shares.(dont knw how property or other details). Now my sisters are dealing with property documents which is not partitioned.Two married and other unmarried.Last day they told me want to sell few property(told me its in two of my sisters name;adhar and all is done by them before the death of my mom and her sisters(i.e. before 1999) but havent registered yet.And when i asked how could they do lik that.they said will give 3 cent share from my younger sisters and 3cent from my mothers share.Its more than 30 cent and for 1 cent cost 4.5 lakh. I heared that they have got thumb impression during last days before there death.but am not sure how they did it.They are telling me late mother property they did in one sister and two aunts property they did in other two sisters name.But then why do they asking; need my signature to sell that land.I am really confused...dont know what they have done to me.What should i do it possible to take my mothers and aunts property without my agrement.I dont think my aunt will do like that to me as they alwz want me to own there property.Plz its very urgent.