Each unit has a kitchen and if i were “renting rooms” it would basically be trying to do 4 units but appearing as renting rooms.

If this is a master, and there is another hall bath for kids, I would only keep the tub if there is room for a good sized shower, double vanity, toilet AND separate soaking tub, which it does not appear there is.  

Most of the crowdfunding sites I've seen appear to be focused on cash flow, and less on appreciation.

The house appears to have an existing loan on it.

It appears Georgia is very landlord-friendly.

Please clarify if you currently own a property or not...from reading your post it appears that you might not. 

From their credit report, it appears they are making regular payments and haven't been late with any payments on anything in several years, so perhaps they just put their wedding on the cards or something and planned to pay it off, but I don't know.

.- Given the fact pattern it appears that they are aiming for a Rent Escrow Action against me in court even though they have no basis.Questions- Should I respond to the repair letter?  

The reason I ask is in my market appraisers often do not look up permits to determine a unit is legal if the unit appears to be legal.  

@Brenda Garcia appear you may be responding like their intimidation tactics are working:(You do need to know the laws better than the tenants!