home land division between brothers

Hi, Actually i am three brothers and one cousin as my father was 2 brothers. So there was a division between my cousin and brothers(3 of us) in the agricultural land and 50-50 of the constructed home. Also there was some land which was left out of constructed area in front of our house so there were division of that as well. Now few portion of the land in unconstructed area which was delivered to my cousins was taken by some third party and we three brothers aslo got parition of the home out of which i took the unconstructed area of the home which fall under our division. Since the land area assigned to my cousin in the unconstructed hone land was legally taken by some third party, he claims to take some of the area of mine where i have started building my home and filed a case in bihar. so wanted advice on below things: 1) What is my rights on reply to my cousin , how should i proceed. 2)we have already provided some area in lieu of that assigned to him by third party which he is not willing to take and interested in only my area. Where i have build the home till plinth level. 3) Also all the 3 brothers are required to provide some areas from there assigned land..why only me.. 4)how shouldbwe go ahead for division, i think of redivision of entire property once again, in that everyone's property already constructed has to be brought down ..why only me?