Attachments to common property

At present one of the lot holders in our Strata Plan is in the process of selling his lot which has a vergola over part of his backyard patio and an split system airconditioning unit attached to the back wall of his townhouse.

The solicitor of a prospective buyer has written to the lot holder requesting a copy of the by-law in which approval of the air conditioning unit has been granted. (no mention has been made of the vergola). Neither the lot holder nor the Executive Committee were aware that permission had to be granted by passing and registering a by-law. In fact, a number of structures have been added to individual lots including other split system air conditioners, a roof mounted solar hot water system and the addition of a sun room to one townhouse. These are the ones the executive Committee is aware of.

Is the prospective buyer's solicitor correct and is the Owners Corporation therefore obliged to deal with such structures by passing and registering by-laws that cover these additions/alterations to a specific lot?