Property dispute

This is a case regarding common passage dispute . A father has by will divide the plain roof in two parts having 600 sq feet to one son and remaining 750 sq feet to other. And will of both the parties has contained the common staircase and other common facilities. The property has on two side ie one son is on front side (on road side) other is on back side(service line) ,but front side party use the common staircase which is on back side of portion ie a party which has 600 sq feet..his around 100 sq.feet portion is waste for dis staircase only and along with it passage to front portion owner (gali). Front owner is using front staircase also and back staircase also mean he has two way front and back. He is using the his stairs which is on his portion and other party is using his staircase from his portion.(means they have separate stairs from there own portion while using there respective roofs. Now the front owner is demanding the passages from back portion owner also the passage from its portion to second floor also....will it be given???? Back portion owner veranda is almost vanish if he gives the permission for this passage. And the gali is surmounted by the front portion owner.. He obstructs the back portion owner to use the two pillars which is on the common passage and the same is obstructed by him on second floor also. What to do in this case please give ur valuable comments..because of no support of one side (obstruction on joining the lenter on one side) all the walls are all most cracked due to earth quakes which was coming so frequently.