This last time I sold it I had it auctioned off just to get rid of it, I had made my money.
What I did was demand 10% down and then negotiated the payment where I could set the term and interest. When I took the house back most often the owners just lost their equity and I paid the closings.
One advantage to them owning instead of renting was they were responsible for the taxes, insurance, care and maintenance.
I would have been thrilled to have any of them pay off the house, it was a hassle to fix it up for each resale.
Your plan with that house is like a buy here pay here dealer.
They sell a car on a 60 month note. But after a down payment and 10 monthly payments... they have made a profit.
If they collect all 60 payments? Bonus! If they have to report the car and resell it? Also Bonus!