My grand father in law property

Hello sir mere papa aur hum sb jamshedpur me rehte 24 ya 23 Saal ki baat hogi jb mere papa aur mere papa ke bade papa sub saath rehte the mere papa just hi bihar se jamshedpur aye the mere dada aur dadI aur chote Chacha Gaon par hI th e us samay mere papa job krte th e kuch samar bad mere papa ke pass kuch Kareeb 70000 rupay th e tb mere Gaon wale Chote Chacha Ne mere papa ko bola tractor kharidne ke kiye to ye baat mere papa ke bade papa jo jamshedpure unke ssth rehte hai unko patamda lag gye tb unhone bola ki tractor leke kya hoga aj kl save jyada fayeda jameen kharidne me milta hai mere papa Bahut seed he the us samay tk ...tb mere papa Ne 70000 rupay aura kuch mere Gaon wale Chacha se kreeb 80000 rupay leke zameen khareed li but us samay mere papa ke bade papa Ne us jameen ki registry apne naam krwa li ..tb unhone bola ye sb sbka hai kisi ko koi diktat nai hogi ...tb mere papa Ne kaha thik hai keen 10 Sall bad mere papa ko bad mami ki tabiyat kharaab ho gye us samay mere papa ke bade papa Ne us zameen ki registry apne wife ke naam krdi..ab us zameen pe to hum ara koi adhikar nai reh gya hai...Kyo ki wo mere papa ki mamI nai thi..so please sir tell me what to do..wo zameen 6 katha ka hai..aur us zameen ki Kim at 3 crore rupay hai...please tell me the solution...