Tranfer of ownership and patta based on will before the death of owner in year 1984

Hi, I brought 50 cent agricultural land in rural tamil nadu. When we checked for the documents it seemed to be clear. So, we registered the land . But recently , the first owner who is now 85 years old applied objection letter in tahsildar office stating that the transfer of land was unknown to him. History of land 1. Ownership in name of first owner in 1976. 2. Ownership and patta tranfer to wife of first owner in 1984( there is no documentation regarding the transfer of ownership and patta, when asked about the transfer they told us that in 1984, government issued patta in name of any family member specifically in name of wife). 3. In 1994, Will was written by first owner for his wife for ownership of land. 4. In 2012, based on will and patta wife sold the land to the third party. Sale deed happened. 5. 3rd person sold to 4th and so on. All are sale deed. I am the 6th person and sale deed happened. My question is that, is it legal to raise objection now and what is the validation period of the objection letter? Thanks, Priti