I mentioned that as an option because the OP sounds like he has very little understanding of RE investing. 

They value a sounding board on deals, situations, or strategy.  

It would allow you to get some of that cash out, you could use that to invest, and it sounds like your existing cash flow could still cover everything.

Sounds way too good to be true.

This sounds like a pretty unique project, but they're pretty flexible and builders are their main clientele. 

Its having a major effect on their budget . 

Alternatively, you could also consider using a mix of both vinyl plank flooring and wall paneling to create a cohesive and cost-effective interior design for your four plex.

This provides a great foundation with a crawlspace which makes it easy to effect plumbing or other repairs, string cable/internet lines, etc.You can see how this works if you look at the pictures on their site.The team is really great and connected me with a lender they have used.

CG is world class. 7 figure flipping I can't remember who does that one but it sounds like a guru name.

So, have enough insurance to keep the target on your insurance limits rather than your families assets.It sounds like an umbrella would be a wise investment for you.