Property rights

My father along with his brothers bought a land of 10 grounds subdividing from a 10 Acre land. In 1975 We are in holding the land and doing business from that date till now. Meanwhile the rest of the land was in hold of the person who sold to us. 10 years ago some people went into the the property and took control of position and case was going on that the person sold to us had forget documents and Thier great great grandfather has a will in their fathers name. They changed documents somehow. Case is going on for 10 years They did not disturb us as we in position for 44 years we have been paying property tax, running business, patta in our name. We even took bank loan with the document. What should I do to safeguard myself in case the person sold to me lost the case. As now there is a big political group involved.