I would have such a by law say that “owners are responsible for any unauthorized changes made to common property within or on their lot” or words to that effect. Many owners are not aware that common property is not only outside their unit. And in my case we have an EC who believes if others can’t see it it is not common property, including exterior features!
Owners in my complex would read such a by law as giving them permission to do unauthorized changes as long as they maintain them. This clause perhaps should be tacked on the end of the clause that says you cannot change common property. We have had an owner change common property without permission. This owner was made to pay for an engineers report and then pay for works to meet standards noted in the report. This unauthorized change cost this owner alot. Should be a penalty attached to the discovery of unauthorized works as a deterrent from people just getting a few friends around and knocking down a wall.