Land Demarcation on ancestral land which had not been aquired yet .

Our Ancestral land which had been peacefully divided between brothers . But now when we are going to acquire the land , the neighbor says he doesn't believe the land reforms done by government 10-15yrs back . He want to make his and ours , square size plots where our land width which has highway facing will be reduced . Which we don't want . Kindly help me with the procedure of land demarcation and please let me know how long approximately it will take for land demarcation legally by court ?