Alteration n society building

Hi I stay in a society apartment with 176 flats. The project amenities are still pending however the water lights lifts and basic things are there to survive . Basically one part is completed except swimming pool gym common amenities I have few questions 1 We want to form association to run the maintenance without taking over any pending amenities and stp management as builder will do that. Builder cannot continue to give water and all as three years they were giving. Now if Association is formed will builder escape ? How to stop that by legal contracts 2 Few owners are so problematic that they have went ahead and installl external pipes and replumber the water line to fix water meter. This is done without legal Noc only on builders email. Can we send legal notice to builder for allowing external construction which is not approved and without legal noc before Association is formed. 3 it might impact in getting OC for this external construction so please advice how to revert this pipe fitting which is done in the society. Thanks rupak