How to regularize a gpa notary

Hi All

My father bought a property in 1986 in Hyderabad via a GPA notary document which was never registered.

Now, my father has expired so is the person from whom my father bought the property and got the GPA assigned.

Let me know the best way to regularize this GPA Notary so that I can sell it without much hassel.

Thanks in advance.

Regards

Syed