In other words, you can test the property before you buy.

The simplest way to achieve what you want is to purchase the property subject-to the existing mortgage.That said, there's a decent amount of training and paperwork you'll want in place before tackling such a transaction.

TEST

Your initial conversations and interviews are a great testing ground for their communication skills.

I would also stress test.

Keep them in their and test run it as a rental.

If the deal looks promising after stress testing then go for it. 

The mother would have to intervene to get a decision on the simplest items.

If your contractor is not familiar with the term, that is the best litmus test to find a different contractor, whether it be an electrician, plumber, carpenter or any other.  

I guess I can imagine what it is, but I see a bit of a problem with offering a property for sale and then telling everyone, sorry it was just a test?