A lease option to the seller for a short time might also work. 

His Son went off to college so he went and bought a house that his son lived in and leased out the spare rooms to cover the mortgage.

We have potential renters who want to lease to own.

If you do, do a short-term lease that ends sometime in the sweet spot of Boston area rentals.- Spend some time thinking about how much to spend.

Lease Option, wholesaling, flipping, etc.

For instance, we had an NN net lease offered by AA rated tenant who wanted to do a sale leaseback.

Do you have a signed lease where they acknowledged unit was in good condition when they signed the lease?

I started out with forms that I downloaded from bigger pockets by Michele and Bruce Fischer --podcast 79 (low-income housing), the templates that came with Buildium (our property managment software), and a lease written by a local lawyer that does the most evictions in our county.

Slap the new tenants name on the lease Then just monitor....

(This should govern your leases as well) you may not need to consult with an attorney JUST for this issue....It's never a bad idea to run things by a real estate attorney anyways.