As Not a Realtor, I'd never agree to this arrangement.

@Zachary HarrisonThe seller has made an arrangement with the broker to sell their property (likely for a variety of reasons).

I’ll preface it with a statement that you should be extremely confident in the capability of the primary flipper, the rehab plan and the ARV of the subject property before ever jumping into this kind of arrangement.  

While some pros don't care about the arrangement being mutually beneficial, some do.

I have had a couple two travel nurses that left a shared living arrangement to pay more at my house due to noise.4.

This sounds like a single family that was converted, so more of a mother-in-law suite arrangement. 

Did they arrange purchase price under market, locate the property and bring buyer and seller together, are they licensed, and a whole bunch of other factors should be weighed.

IMO the lenders will work out some kind of payment arrangements with those borrowers who can afford to pay - a loan modification with a higher monthly payment or a loan modification that puts the arrears into a second mortgage that is payable on sale or at a refi or at payoff of the primary mortgage.

I'd talk to her and remind her she needs to let you know if things are broken and together you will arrange to get them fixed. 

This strategy can be beneficial in a rising market or if the investor needs time to arrange financing.Subject To: describes a method of purchasing property where the buyer takes over the existing mortgage payments without formally assuming the loan.