Illigal possession and podi difference

Hello In one survey number there is total 4.27 acres of land My grandfather had bought 2.27 acres of land in 1978 . In the same survey number two (P1 AND P2) more people had bought 1 acre each . But at the time of podi and Sketch . My grandfather had got 1.35 acres of land and the remaining land went to other two buyers. But as per RTC information we have 2.27 acre . But in akarband and atlas copy only 1.35 acre is shown. Due to this difference , P1 and P2 are in illigal possession of our remaining land and are not denying to give the land How should I proceed now ? Kindly let me know