You cannot register a society as it required 7 members. The law relating to terrace etc is as follows:
Owning or occupying the terrace of a housing society building is unfair and illegal. The builder/developer has no right to sell the terrace.
Some developers of co-operative housing societies resort to the unfair practice of selling the rooftop / terrace. It has also come to light that in some housing societies, owners of the flats at the top floor claim ownership of the terrace and dissuade other owners from using the same. Both these actions are contrary to the stipulations as per law.
According to Section 4 (1A), (iii), (viii), (x) and Section 10(1) of Maharashtra Ownership Flats Act, 1963, the builder/developer has no right to sell the terrace. The builder also does not have the authority to sell the terrace of a building. As per law, all open spaces in a building, including the terrace is a common easement for the benefit of all the members who are entitled to enjoy the same as shown in the Municipal Corporation records. No single member can appropriate and deprive others of the benefit of common easement. When the BMC sanctions a building plan the terrace is not taken into consideration for the purpose of calculation of Floor Space Index as it is for the use and benefit of all the members (flat owners) of that society.
Owning or occupying the terrace of a society building is not permitted by law and if any body does that it is totally illegal. The law and BMC rules are amply unambiguous and clear in this regard and there is no provision at all under which the terrace of a society building can be sold or bought. There has been a landmark judgment delivered by the Honorable Mumbai High Court in 1999 in this regard while adjudicating on writ petition No. 4577 of 1985, in the matter of Smt. Ramagauri Keshavlal Virani V/s Om Walkeshwar Triveni Co-operative Housing Society Ltd & others. Adv. Vinod Sampat, an expert in Co-operative Housing Society matters is also of the same opinion and says that no person can own, sell or buy the terrace of a Co-operative Housing Society building.
Hence, any one who indulges in such unfair and illegal practices does so at his own peril because it has got no legal sanction and is always subject to litigation; a person doing so will be on the wrong side of law.