You collect the details:
1. The properties that were in the name of great grandfather:
2. The share of properties that were allotted to your grandfather;
3. whether your grandfather died intestate, in that case how many legal theirs were there to your grandfather including your own father;
4. How much shall be your father be entitled out of your grandfather's share in the property;
5. How many properties were sold out of the total properties that were lying on your grandfather at the time of his death and how share of properties were given to your father by the people who sold the properties of your grandfather;
6. You can file a partition suit claiming your father's share in all the properties that were sold and unsold so far after discussing with a local advocate and proceed.