Property related.

My grand father (father's father) has two individual buildings, both earned on his own. One building in 8 cents, other is 4 cents. He has 3 children - 1st daughter (born in 1950, died), - she has 3 children - 2 daughters and 1 son 2nd son (born in 1956, died) ( my father ) - he has 2 children (1 son, 1 daughter) 3rd daughter (born in 1966, alive) - she has 2 children (1 son, 1 daughter) My grand father did not wrote any will. After he died in 1991, all his children created a FAKE WILL like my grand father has written and divided the shares. My grand mother, father and my aunts have signed and divided the property as per fake will in 1992. The signature in the fake will is NO match to my grand father's signature and can be easily proven wrong. As per fake will, major portion went to my grand mother and that too the will mentions she has complete authority to even sell the property on her own decision. It is registered in her name from 1992 till date. Now my small aunt put my grand mother in her grip and my grand mother is ready to write all the property she got from the fake will to my smaller aunt. Question: Is it possible to cancel the fake will created in 1992 (signature mismatch can be proven easily) If cancelled, what will be the share of property to my aunt's, father and grand mother ? What will be the share if in case I cancel the fake will after my grand mother's death ?