These developments often need to deal with changes in ownership groups.

Beneficial Ownership Information Reporting (BOIR)Have you heard about this?

Look for ownership name in LLC and address's other than property, these 2 things are very good indicators it's a rental property. 

The second outcome of purchasing a loan in default is foreclosing and ending up with property ownership.   

This would require tenancy in common which lenders typically won’t allowTransferring ownership from personal names to LLC is straight forward with a deed transfer and re-assigning the tenant leases.

I'm ASSUMING (a bad idea, I know) that they were a married couple and had joint ownership. 

My wife still needs to have at least 50% ownership in the property since she is on the loan.I am currently the sole 100% owner of this SMLLC formed in CA.

And then there's the layers of 30% of income to home ownership vs. 30% of income to rent.  

You can do this with a simple, one-page addendum, or even a written statement added to the existing lease and signed by you and the tenant.Example:This lease agreement is hereby amended to reflect the change in ownership of the rental property located at 123 Straight Street, Cody, WY 82414.

The tenant-buyer has time to fix their credit and save more money for a down payment during the option period, then exercises their option - fulfilling their desire for home ownership.