Undivided property sold

We have a piece of land in our village of area 56 dismil in up . The land is located on main road , so 6 dismil land has been used in the road after this the actual remaining land is nearabout 50 dismil . My father along with his 2 brothers are owning that land . Distribution of land has not been done yet . Last year my fathers elder brother sold his part of land 18.67 dismil with any info or discussion with his brothers . The question here arises that first the land is sold without any info or dividation second he have sold more area that what is actually present . Out of 56 dismil we have only 50 dismil with us rest of 6 dismil has been used in the road , so the remainig 50 dismil will have an equal share of 16.6 dismil but he sold 18.67 . So before khariz dakil my father and his elder brother filed an objection letter in court that the actual land is less than the land sold . After that my 2 no tau ji is not willing to do settlements then the purchasing party had done settlements with us and the actual land is divided equally in court but after few days he buid up a wall in our share of nearabout 135 foot now he is not ready to remove his wall he is saying that he had purchase 18.67 and my land is less so i will accquire more as i have paid for more n also made his registry of 18.67 by some cheating methods . So what do now , firstly we want to know that did anybody can sell the land wch comes under public road , 2 can his registry of 18.67 dismil be cancelled through any means.