Some have done owner financing with an agreement to pay all interest and equity splits when the home sells others have done it where they do a quitclaim adding their name onto title with the seller so once rehab is done the seller can't try and cut you out of the deal. 

The exact split will depend on your agreement with the brokerage.

We expressed all our frustrations and eventually the conversation ended with Lendbase saying they’d give us $1,000 if we signed a non-disparagement agreement.

However, we need to be clear that with a subject to transaction the debt is secured by the property; most often personal liability via a guarantee rests and remains with the seller/original borrower, the property buyer has no responsibility for the debt and no personal liability UNLESS he modified this status by contract agreement with the seller; in which case he may be liable to the seller only. 

Who pays when the resident breaks the agreement and quits paying? 

We drafted a short-term “use agreement” giving her a couple of months to find a new spot for her outdoor furniture and tools.

However, there isn't a standard form like a NAR lease agreement; it just needs to provide some general information.

So I'd need to figure out an agreement/return between A and B, and then I'd need to figure out an agreement/return between (A&B) and C.

Not as interested in how to paper a partnership agreement, really most interested in how others have successfully handled the alignment of interests component to business partnerships that span an entire portfolio.

@Victor YangWhy are you not reaching out to a NC real estate attorney to draw up a document that spells out the agreement that you are looking to do with the tenant?