I do not want to kick her to the street (she says they have no money left to make new arrangements). 

Or if you hire a contractor, and there is a younger guy in the crew that probably lives with their parents, much easier to arrange. 

So, in a nutshell, your arrangement with your relative and how the profits are split when properties are sold depends on the terms you agreed upon when setting up the partnership.

You need a PPM and a TIC arrangement for holding title to the property.

You are paying for your son's living arrangement by giving him $200,000 and she is getting her rent paid for by some other guy.

I currently own a 9 unit multi-family and a mixed use fourplex both of which has commercial financing, so I'm familiar with the typical financing arrangements and valuation. 

I think that's enough to arrange a meetup and network. 

Yes, this is an unfortunate situation however the tenant knew this was coming and failed to make other arrangements. 

As a quick addendum, the last time I was in small claims court trying to recover several thousand dollars from some tenants, I brought with me several pounds of documents sorted out within about a dozen folders.After the Magistrate asked me to state my case, I spent at least 30 seconds arranging the neatly-labeled folders out upon the Plaintiff's desk before I said a word.

If this is more of an ongoing financial matter rather than just a one-off family situation/job loss/etc, then you could be headed into some difficult months ahead (ie. if the rent increases to compensate for the missed July payment, you have to consider the reasons why that payment was missed in the first place and factor that into the arrangement for the coming months, if you're going to proceed with the increased rent strategy).