don’t wait .
the first thing the OC should do is issue a notice to comply . Look at your bylaws but there will be one about damage to common property.
The condition of the lot owner getting approval should br
a) a bylaw for the addition
b) approval by the council. Any such structure requires approval by council, irrespective thst the OC has approved.
Hopefullythe owner plays along, but if the owner is reluctant you can take it all the way to NCAT.