Intestate Agri land to be purchased

Dear Sir, We are planning to buy a property (Agriculture land) in Tirunelveli area, tamilnadu. The Owner of the property is a christian. The property includes approximately 25 acres with its own income MRS. Victoria, taken in 1960. In addition, about 5 acres of land was donated to her husband by the year 1984 They have six children. Only one person is living in the town where the property is available. Others have migrated to different parts. The couple (Victoria) died before 2000 without writing a will. Their 6 sons have got a legal heir document from the register office upon demise of their parents. In the year 2001, the 5 heirs gave power to one the brother living in the same town through a power document The power document was very generic without referring to specific assets which we are planning to purchase. when we enquired in VAO office they mentioned that the registration can be carried out with the single person having power. A lawyer told that any heirs of the 5 sons have right towards the property and have rights to proceed a legal case in future. We are therefore unable to take any decision. It's about how to obtain the correct information.