I have dakhil of land in register II but not sale deed

My aunty was an issue less lady, her husband abandoned her. At the time they were together a land of 6 acres was bought by her husband in her name and in same plot he bought 6 acres for himself. After 10 years , the demand of entire 12 acres came in the name of my aunty. After some.years her husband drove her out from his house and had another wife. As my aunty had been driven out she couldn't get any deed or paper with her. As she was issueless she transferred all her property to me through registered will. As now she has died , a claimant has come out saying that my aunt's husband sold 6 acre to him and showed a deed. I even today paying the revenue of total 12 acres. Pls tell me what is my position in the case, also I have heard that an issue less person can't sell his property without consent of his wife. I am also trying to trace out the basis on which the the register II entry had come to effect for entire 12 acres. What will be my position if I cannot get the copy of sale deed /gift deed or whatever was the reason of transfer of 6 acre of land of aunt's husband in the name of my aunt.