Noc for sale of flat

Dear Sir, Myself Lalit Nemade living in registered housing society in Maharashtra in which currently I am secretary of the society .In our society one of the flat member had open terrace ( open from roof only ) which he covered with metal sheets and also done changes in original structure given by builder where he did not changed any water outlet but added wall and bathroom in open terrace and shifted position of doors given by builder for bathroom and for this he has done without given any prior intimation to society and now he wants to sale his flat for which he applied to committee but as few society member has objected as they consider that he has done structural changes so society should not give NOC for sale of flat and ask him to restore his flat as per original structure . Earlier committee issued him written notice that they will initiate action against him and inform local corporation about illegal construction within 30 days but they did not initiated any such action . Now he had given notice to committee that if NOC for sale of flat not given to him within certain period he will initiate legal action against office bearer of the society .So i would like to know whether as per bye laws can we hold NOC and what will be legal impact of same to the office bearer if any legal action initiated by him as it will cost society to hire legal expert to safe guard them selves please advise on this at [deleted]