Cancellation of property registration which used fake GPA
I have inherited a residential land (40x60ft) from my father who passed away in year 2000. I am in the process of transferring the Khata to my name using inheritance by way of family tree. My father has not left any Will. I am the only son, and my sister who is elder to me, was married off in 1984. My mother, who stays with me, has consented to transfer the kana to my name.
When I applied for the encumbrance certificate, I found that someone has registered a fake GPA with respect to the property as if executed by my late father in year 2010. Basically someone has impersonated by father and has signed the GPA in the registrar's office providing his photograph (not my father's). Within three months, the person who is the GPA holder, has sold the property to two persons by dividing the property into two pieces of 20x60ft each.
What is the course of action for me to restore the ownership to my father and to transfer the property to my name. How do I get the fake GPA and subsequent sale deeds cancelled by the sub-registrar??