Have a look in your Strata Plan. It will show how far above ground your owner’s property extends – perhaps 3 metres.
The strata plan will show how far the lot air space extends above the terrace. The lot owner should pay for the air space used above that.
If a by-law is needed, draft it and call a general meeting to consider it. Otherwise the roof comes down.
The lot owner should have the by-law drafted, then the OC can consider it at a general meeting (which the lot owner should also pay for). This process should not cost the strata scheme a cent.