1. In whose name is the property in the municipal records at present.
2. Was it a joint family property or it had been partitioned between your father's siblings and if partition has taken place, whether the deed of partition is existing.
3. Whether your grand father had executed a WILL?.
4. Did your grand father died intestate(without writing a WILL).
5. Assuming that your grand father died intestate in 1963, then the property would devolve equally between your grand mother, 4 sons and 2 daughters, i.e., 1/7th share in the property, if the property had not been partitioned till 2005.
6. Your grand father had 6 children and upon his death without writing a WILL, the property would be divided into 7 shares(including grand mother's share)-if grand mother is dead, then the property would be divided equally between your grand parents children. If any of the child/children are dead, then the property would devolve to his wife & children in that 1 share, subject to grand father's property has not been parititioned earlier to the year 2005 and was intact. In that case the grand daughters will have the right in their father's share of the property.