Land grabbing

Two brothers B1, B2 bought 3 acres land from a third person in 1970. In a survey no. 94, which they subdivied into 94/1, 94/2, 94/3. These brothers did not made any markings as to show which land belong to whom out of the given 3 acres. These entries are still In Mandal Revenue office records when I applied for pahani-nakal for the last 25 years. B1 share 94/1 and 94/2, B2 share94/3. B1 invested for 2 acres, B2 for 1 acre. Being own brothers this 3 acre purchase was a single transaction. B1, B2 both expired long ago. Legal heirs (grandson's )of B1 sold entire 94/1, 94/2 of thier ancestral property. Not only this they sold more than half in 94/3 part. Out of 1 acre there is hardly 1000 yards left. Legal heirs of B2 came to know this situation very late. Now we the legal heirs of B2 don't have any legal heir certificate (LHC) also, as transfer of name was never done. As I came to know obtaining LHC is expensive and time consuming. By the time we get LHC the opposition sells the remaining 1000 yards also. May I please seek some advice here. Thanks for this web portal.it is really informative.