Please verify with zoning and ask them for a verification letter so you can have approval on hand.

The letters are pretty vague and when you look on the EPA website they talk about a 10-year initiative.

Write targeted letters yourself saying you own and live in a multi in the area and are looking to expand.

Quote from @Donna Johnson: Quote from @Judy Foster: we too have tried a small investment in their notes and we got the same letter yesterday. 

If it came from your parents, you may need a gift letter from them stating that it's gift and does not need to be repaid.

Check county recordsUse online search tools like PropStream, Reonomy, PropertyShark, etc.Use local GIS mapping tools (ask your county)Search online directories for LLC or TrustTalk to neighborsHire a skip tracerSend a letter to the propertyThere are a lot of options.

Thank for that information as I am having the same problem but the family is still in the property and won't respond to the attorney that send them a lot of letter and phone call.

I’m considering having a lawyer send them a certified letter, though I know that will still come with a significant fee, which is still preferable to full service.

However I just received a very concerning letter from the Fire Marshall Office saying I need to provide a notarized letter within 5 days stating I will not have more than 12 occupants in the cabin until I change the Certificate of Occupancy which would be devastating to my bookings.  

Rather than hire as many sales people to do follow ups--set up automated text messages, emails, letters, or postcards to be sent to your best prospects.- Podio has really good integration with other services--like RightSignature for eSignature, Google Docs/Drive, Dropbox, Twilio for SMS, Lob for physical mail--either for marketing or other workflows like invoicing, and a ton of other services.