Can you be a tenant in a house you financed?

[Gabe C.]

My grandparents are in their mid 80s, sold their house last year to rent and simplify life. Their rent got jacked up because the market exploded, and now they want to live in a house again for rent control... but understandably want ZERO to do with taking care of it. They called me to see if I'd be interested in helping. I thought maybe this could work...

My grandparents open a promissory note to lend me the money to buy a house for them, and then move in. My property manager can take care of the place, absolving them of headaches. They would have to pay me rent to cover costs, but I would basically give most of it back to them with interest immediately (much more than they'd get on their crappy CDs) to cover the note. That seems necessary for the books to work, but sounds weird. 

Does this seem legitimate?