Want to install water tank on terrace

We have a property in Delhi. This property belongs to my father with 50% share and two of my uncle's with 25% share each. They (my father & uncle's) with mutual understanding made an "Agreement for Family Settlement and Partition" on Rs.2.00 stamp paper in which my father's portion is Ground Floor. One uncle's portion is First Floor Front Side and open Terrace of Second Floor Front Side. Another uncle's portion is First Floor Back Side and open Terrace of Second Floor Back Side. On Terrace of Second Floor Front Side there was one old Cemented Water Tank from which Boring (Submersible) water is coming to Ground Floor, First Floor Front Side and First Floor Back Side. Now this Boring (Submersible) water Level has gone down and many of plumber's denied that this Boring (Submersible) will not work any more. So Me and my brother both with our family's living on Ground Floor decided to install individual water tank because old cemented water tank is leaking from various places and is in very bad condition. Regarding this we approach to our uncle's but they denied us to install water tank on Terrace saying as per "Agreement for Family Settlement and Partition" Terrace belongs to them and not allow us to install Water Tank on Terrace. Kindly give us your valuable advice that we both brother's have a right to install Water Tank on Terrace or not.