Harrassment to my parents for property

My parents who are senior citizens are been humiliated and harrassed evrytime they move in to their native place house which is a ancestral property and not allowed to enter their own house and been denied forcefully by the sons and inlaws of their brothers. They have forcefully acquired all the land as well They carried out burglary in our house almost 10 to 11 yrs back and burnt all expensive furniture's in front of whole village as we reside in Mumbai they carried all this in our absence. Before this criminal activities they use to sold and sell anything and didn't use to give any kind of share to my parents. Everytime they demand money from the flat where we stay in Mumbai which my grandfather gave to my father event hough all the papers are legally in my father's name. Even though my parents said they will give some amt to them out of goodwill they carried away all the criminal activities like burglary at our native place homes Selling the properties in which my parents had a share and not giving him anything. Pls advice how to protect my parents and ourselves from this goons and lawfully take our share in our native place properties. Tks