Illegal agricultural land registration of son from mother in Telangana

Point 1. We got a land(Sy. no: 99/ ఉ - 10 Acres . 20 Guntas and Sy. no: 99/ ఈ/ - 01 Acre. 00 Guntas) from our grand father, on his expiry revenue department has transferred the land on our grand mother and passbook was issued on our grand mother name. Our grand mother has 4 sons and 2 daughters. 3rd Son took my grand mother to MRO(Revenue) office by telling her that she need to sign to get her monthly pension but he had registered 50% part of the above said land i.e. (Sy. no: 99/ఉ - 05 Acres . 10 Guntas and Sy. no: 99/ఈ/ - 00 Acre. 20 Guntas). After he done that now other three sons has registered the remaining the land approximately 17% for each son. Now our grand mother is our side and she always says land should be divided equally among 4 members. How should we proceed here ? Do we get our land back ? If we file a Court and Revenue Case could we win ? Point 2. Also one more point here our grand mother 2 daughters are asking for money if they file case on our land do they have rights their marriage was happened before 1985. We have not sold any of our land till now. If they okay to take money to give NOC at what point of time we should give them and what proofs we should take from them. Could you please give me advises on my Point 1 & 2