Take the appropriate measures to buy the land and do the transfer and KEEP YOUR MOUTH SHUT about the building. If anything is mentioned about it, it was all legal when it was built and that should be sufficient. Hypothetically, if two 20-storey buildings are built side by side an then one is sold off, does one have to be demolished? If a person severs their lot 8 feet from their house, does the house have to be demolished? I strongly suspect the by-law applies to new construction and the folks at city hall are too damn lazy to look it up!