Property rights of grandchildren.

My Grandfather had a piece of land owned by himself. When he expired there was no will made. He has 2 sons and 2 daughters. After he expired all the property khathas transferred to elder sons name and my father is the 2nd son. At the time of transfer, elder son gave some paltry compensation to my father and 2 other sisters. I was 19 years of age at that time and not signed any of the documents.

I was not knowing all these till the property was kept for sale very recently. I wanted to know my rights in the property. Can i claim for the property now? What are the legal procedures for this? Was the transfer for Khathas to elder son valid without my signature even though i was a major at that time? If the property is now sold to someone else will my signature in the sale agreement necessary?