You kind of jumped the gun with the purchase in evaluating the entire picture prior to purchase, but it is what is right?

You may already know this (you should know this), the JADU requires owner occupancy on the property to be rented as an individual unit.  

However, there are some bridge loans that help owners capture some of their equity to buy a replacement property, while listing their current home for sale.

An "owner's title policy" is purchased (typically) by the seller for benefit of the buyer. 

To address this, we verify the property owner per government records and use this information to vet imposters.Anything that seems suspicious will lead to us requesting an acceptable Letter of Explanation to address.Analyze IncomeMany landlords require a month of paystubs from applicants and just use these to calculate a monthly qualifying income.

Many are private owners just subsidizing their mortgage or they would not be able to afford the house without renting it out much of the season.

Or ask the third owner if they would also consider selling, so the whole property is sold.Whether a partnership or LLC, follow the Operating agreement. 

Does the owner use property management now or manage themselves? 

Ask them if they want to sell their house or keep it.100 out of 100 will tell you they want to keep their house.The same goes for absentee owners, probate, tax liens, etc.

If the sign is tired, so is the self-managing owner.