Can I Buy A Agricultre Property With Only Patta On All The Family Members.

The 3rd generation is trying to sell the agricultural land and they lost document in fire accident (claiming that they have FIR copy). 2nd Generation had 4 family (4 parts) and then each have it's family tree. They have patta on all their name. We could not get any duplicate copy in last 70yrs of EC check. Shall we buy and if so, what should we do.