Illegal Sale of Land by cousin

Hi, My grand father purchased piece of Land and build shops in them . The land didnt have registry however it was entered in the nagar palika documents under his name( Called Patte ki Zamin). Now i nthe family, grand father died and grand mother also no more. They have two sons ( my father and Tauji) and daughters. One of them being my father who along with my mother also no more. My Tauji is also no more. The shops were rented and Tauji and his son were getting the rental payment and during all this time the land was under my grand father name only. Post Tauji's death, the entry in nagar palika records were changed first to My Aunt ( Tauji's wife) name and then to cousin brother's name. Then he sold this land to someone and that buyer also got this registered under his name. I got to know about this few weeks back. Could you please advise me next course of action, what all IPC other than 420 i can put to him so as to get this land transferred under my name and all the deals cancelled which was illegal also to get him punished. Im my father's son and have two sister(married)