Dispute in Terrace usage at my Flat, Poonamallee, Chennai

Dear Sir,/Mam, I am NRI. I bought a flat at Poonamallee at Oct.2014 and my family staying there from Feb.2015. Our building having total 4 nos of flats as specified below My Flat building’s Facing is East and road on north south direction. Ground Floor : roadside Parking and 1 No. of 2BHK with rear side landscaping (G1) First floor : Roadside 1 No. of single bedroom, staircase afterwards 1 No.of 2BHK (F1) 2nd Floor : Roadside 1 No. of single bedroom, staircase afterwards Open terrace 3rd Floor : Roadside staircase rood with open terrace. My flat is in first floor double bed room (F1) and above my roof is no building, its open terrace where 2nd floor flat family is directly can access. Now 2nd floor family is fully using terrace above my roof and they have damaged. 2nd floor single bedroom also having separate open terrace with covered staircase but they are all the times at my terrace only. When we asked about this they are speaking nonsense and told us that “Open terrace is common area and no one have the rights to tell them”. They placed a dust pin in terrace and not removing even after repeated request. We met lot of unconvinced. Ground floor family and fist floor single bedroom family stopped to coming up due to the second floor family occupied with unwanted materials on staircase & Terrance but terrace above his flat is very neat and clean where only water tank is there. He denied to share the maintenance cost also. Kindly note my proposal as below: I want to separate the Open Terrace Area without exclusive right of the all flat owners. 1. Open Terrace Area on 2nd Floor Single bedroom Flat : the same 2nd floor flat owner can use the same on daily basis and other 3 flat owners can access only for maintenance works as and when required 2. Open Terrace Area on 1st Floor double bedroom Flat : Ground floor flat owner and 1st floor flat owners can use the same on daily basis and 2nd floor flat owner can access only for maintenance works Or 3. Share and Mark the Terrace area proportionately for flat owners and allow them to use the daily basis for those are having the shares in the respective terrace area and others can only access for maintenance works such as water tank repair, Dish fixing and etc. accordingly share the maintenance cost to be incurred in respective open terrace area. My Builder is not taking any action and he is demanding money now. Kindly advise me “What is correct on legal?”. How we can avoid the harassment by 2nd floor family. My wife and daughter is alone at flat and I am bit scare to ask them strongly. Kindly reply me please Thanks & Regards, Jeganathan S Manager(Tendering&Contracts) SMC INFRA LLC,P.O box 1126, PC 130, Azaiba, Sultanate of Oman GSM: +[deleted], Mail: [deleted]