In the case if I don't receive a new address, I'd probably send the letter to my property where the tenant was living and let USPS mail forward the letter. 

For context, the tenant is an elderly lady in her 70's who lives alone.

And there are even more carriers who would insure co-living rental w/o owner-occupied - for example Obie.

What would you do with your current residence if you planned on living in the new one to get an FHA loan?

My wife's siblings have built 2 house on this land as there own houses they are living in The property is a total of 15 acre and each siblings got a portion of the property.

You can probably just go ahead and live in that 5th unit, but I believe whenever you go to refinance it with a bank or what not, the 5th unit will make it require a commercial loan and not residential regardless of what the county records show the property to be. 

I’ve lived in my current single family home since 2020.

If you want to run a charity for your relative, then you could just help them with the mortgage, or buy the house from them for a great rate and let them live there cheaply.

Quote from @John Busch: Truly appreciate the multiple responses and look forward to continuing our communication as we live in Southern CA and do not have many contacts in that part of the county. 

I really believe that we live in a time where all the information you need to do just about anything is available for free online.