Distribution of Self Acquired land amongst brothers

My father has bought a huge plot some 30 yrs back. He distributed a portion of the plot to his 4 younger brothers and they have been residing there since then.Among the 4 brothers, 3 brothers have fenced their boundaries but there is no fencing between one of the 4 brothers and my father. This is the problem. My father died 5 years back and now I want to settle the land so as to know my actual portion of land and lay demarcation. They are forcing me to measure the whole plot in sq ft basis and redistribute again. Is there any logic? they are doing so because my potion of land is slight bigger and there are concrete structures also.So how can I give that which my father has built the structures.My father bought the land with his money exclusively but later on he added their names in the document .But my father has not given any deed or will to them.I want to know whether I have the right over the whole plot still. Do they have any right to interfere if I go for demarcation according to myself between one of the 4 brother and me which I mentioned earlier.In such situation what am i supposed to do.