Neighbor built room and boundary wall in my land, is it legal?

My grandfather's father were two brothers(A & B).A is my grandfather's father and B is my grandfather's uncle. B has three girls, Half of B's land sold by himself and half of land he convert of his 2nd wife before die. Before death of 2nd wife, she transfer her portion to her sister @ C. At that time his girls claim for property but at that time there was no such laws so they can won the case and they lost the case. Later on brother A suited a case of partition and by law property is divided with proper manner. After partition we found there is one extra khasara number / point that is in the name of brother A (shamlat mahal hasab rasad maal guzari ) that was not covered under combined land of A & B, When we asked patwari about this number he told that this number is in the name of A . After patwari marked that number and we found that in around 60% of land of that number already captured by C and in 20% area they construct the room and 40% area still open but constructed the wall.