Cheated while land allocation by Grandfather how to proceed legally

Hello Sir, We are a middle class fmy, where my Dad (elder among 6 Bro.) worked in Agra for 25-30 yrs. During land partition, his Bro's manipulated the deed and the land which my Dad received to build house is not given proper road for vehicle to get it, my Dad didn't filed any case due to family relationship(one of his Bro. filed a case), now my Dad and Mom is staying in the land alloted for more than 9-10 years, now one of Bro. wants to build a boundary which will only allow walking space for my parents, no human reasoning or love shown by Bro's, is there any way this can be stopped and get at least as reasonable space to access this land.