Grand daughter, grand claim share of her mother's share of ancestral property of her father

The grandfather of my mother is having ancestral Property for ages .Now my mothers two brothers tried to confiscate her share of ancestral agri property with manipulated agreements executed when her daughter and son who are majors have not given consent to the alleged partial partition of their family properties, which is under civil dispute in the local district courts . Can the grand children seek cancellation of such illegal agreement on partial partition of ancestral property of my brother and her two brothers when their parents exists and grand father of my mother exists but aged (over 83 Years) with no balance of mind to apply at the time of partial family settlement . We (grand children) contend to cancel to the alleged partial settlement of the property of one state alone (by way of alleged consent and relinquishment agreements ) which are under question before the civilian court in Karnataka and now claiming equitable rights for whole of family property . The property is spread in Karnataka and Andhra