Brother in law started construction on ancestral property

Hellow sir, I am having a dispute with my brother in law with respect to property he is not providing a share in property I am sharing the detail about the property here: 1. The notary of the land is on my grandfather's name and he is no more 2. There is no registry of the concerned property on anybody's name in my family 3. The person who sold his property to my grandfather had also passed away. 4. My brother in law is carrying on the construction work on the concerned land Tell me the solution which I can use to either take the possession of that property or dial and remains with No 1