In addition even after the building is fully licenced the previously unlicenced annex will always be treated different from the house that was built with a correct licence from the start.

This video is a great start and includes a lot of sample images (good and bad).

Does anyone know what I can do to treat it ?

Honestly if the property taxes are enough to make the rentals a bad deal I’d suggest selling.

If you just hire the cheapest or first PMC you speak with and it turns into a bad experience, please don’t assume ALL PMC’s are bad and start trashing PMC’s in general.

But it's a risk.If the PM is that bad, I suggest you do some research and find another manager.Remember: cheaper doesn't mean you'll make more money.Start by going to www.narpm.org to search their directory of managers.

Use surveys to gather feedback on their experience.When tenants feel valued and respected, they’re more likely to take care of the property and renew their leases, saving owners time and money.Fairness with VendorsVendors play a crucial role in maintaining properties, and treating them fairly ensures they remain reliable partners.

Honestly, over leveraging is a really bad idea at this time (just my 2 cents). 

I do have folks that don't book because of that.That is a good thing as not understanding the distance to get places will create bad blood and cause those 2 and 3 star reviews which no one wants to see.Like , our place isn't cheap so we don't get the folks that destroy places.The bottom line is that you are renting out an expensive asset to strangers for 3-10 days or whatever.

Leveraging business credit for a real estate deal, especially if that credit is only interest-free for a short window, isn’t automatically a bad idea…but it’s definitely not for everyone.