You also could do a nicer house hack if you wanted to make it a permanent arrangement.

I could be interested in such an arrangement.  

LTR is passive where STR is active & you need be involve in book questions, cleaning arrangement, etc (unless you hire management company). 

They are requesting a month to month arrangement.

Part of the arrangement was that I could attend the events as well, which was great.

If she was primary, then you would be getting child support or just paying to raise a kid.It is possible with her being married now, that you could go to court and push for a 50/50 co-parenting arrangement, where she no longer pays money. 

For any asset purchase you have to find a deal, due diligence it, negotiate the sale, arrange financing etc.

They told me that people who are staying in a co-living arrangement often are lower income earners, so they struggle to budget monthly.

I have a family member who owns property in a north jersey location,  the property currently has a 99 year NNN lease arrangement to be restructured every 5 years. 

Could a partnership or LLC provide a vehicle for this type of arrangement?