Patta and chitta are enough to prove the title before the court

my father bought a piece of land as someone mortgaged the land (orally) later since the debt was not repaid my father took possession of the land and this happened in year-1960, now my cousin brothers (from my father's side) are seeking for share in that land by claiming that the land was obtained whilst everyone was living jointly. The only document to prove the title is adangal which is in the name of my fahter, I need to know would this suffice to prove my father's title. my cousins don't have any documentry proof to prove there case.