In addition to the suggestion by Jimmy-T, you could go to your local council and ask to speak to someone about the history of the strata plan.
I’m not sure it matters. If the sail is a fitting or fixture, would it necessarily be on the original development application? There’s also a possibility that it was installed at a later date by the developer, as they took a long time to sell the units on the top floor (18 months).
In any case, if there’s no by-law in place to pass the responsibility of the maintenance to an individual lot owner, then it must, by default, remain the responsibility of the OC.
