I was a Marine before I became a Solider so I still secretly root for Navy.

@Zak SmithI’m rooting for you!

Your uncle may root for you and respect you - but may not necessarily trust you with making a $50K or $100k investment for him. 

;)) Good luck warrior, I'm rooting for you!

I agree with the others that HVAC issues as root cause seems a bit suspect.

On the other hand, if you saw him treat his mother in a way that you wanted to be treated, then root out the problem, develop a strategy, and move forward together.

Now they're settling down and starting families, have careers locking in, established roots in the community, etc. 

Adding more housing is important but the way this occurred was grass roots work by younger, dynamic people who care about having places other than a SFH home. 

This is likely the root cause of some of the other issues we have been battling for the last several years.

The only tip I would give you is to relax and take a deep breath, consult more people ( which you are doing right here on BP) and keep running the numbers.I hope it works out and am rooting for you.