Previously completed housing building without rera

NOC fromother flat owners is a mandatory requirement and they also will be entitled to an additional FSI.

If the builder intends to sell those 3 new flats, it becomes a new phase/project and must be registered under MahaRERA before advertisement or booking, FAILURE TO REGISTERE MAY ATTRACT PENAL PROVISIONS. 

Builder cannot unilaterally construct additional flats without consent of existing flat purchasers, unless:

The right to additional construction was clearly disclosed in original agreement and layout + FSI potential was disclosed at time of sale.

If additional construction is based on newly available FSI after completion, courts generally hold consent of existing flat owners is required.

Additional construction requires proper approval of competent authorities (including MRERA) as per rules governing subject matter.

NOC of existing flat owners is not mandatory. 

Provision for parking is an internal issue depending upon availability of space, which cannot form part of additional construction in increased FSI.