Legal heirs of paternal deceased grandmother property

I am Mohan from Chennai, who seeks legal advice on the ownership of paternal grandmother property. We are three sons and my father was passed away on 2000 and my grandmother on 1998. My grandmother has a an acre of land with original patram document and mentioned the legal heir of son and his son can enjoy the ownership of that land after her death. My grandmother has one son and two daughters, two daughters were married on 1967 and one aunt is died on 2009 and her husband is fighting for property rights and trying to sell the acre of land to other person. Uncle has no legal rights over that property and cut down 100 palm trees which are more than 100 yrs old without our knowledge. I have consulted advocate, each is giving different opinion on the same issue. One advocate says, there is no legal rights for the daughter who are married before 1987 and another advocate says, legal right is their to own a part of land. How it is possible? kindly clarify me on this issue to seek legal opinion to get justice for us.