Each of those deals have favorable IRR > 15%; so should I check for something else? 

It's also upsetting her kids' skin because it is so harsh, so a simple drinking water filter isn't a favored solution. 

Asking for the volume to be reduced and explaining why diplomatically - rather than just making the demand - makes it a favor to you rather than a complaint.

I know of three and I'll list them here in alphabetical order so as not to favor one over the other.

Considering your situation, holding onto your current duplex with its strong cash flow and exploring refinancing later when market conditions are more favorable and you have built up more equity seems advisable.

And a little tip...if you can move all or even some of the properties you own into a trust, LLC, or whatever entity is right for you, the DTI clears up and you look favorable to lenders.

Owner financing could indeed be a viable option given your good relationship with the owner and the favorable mortgage terms.

I beleive there's plenty of opportunties on the MLS, but they are usually categorized incorrectly i.e. a property possessing favorable zoning listed under the single family category, public records incorrectly listed the square footage, or instances where  BRIGHT MLS doesn't track zoning changes real time with recently introduced zoning bills.

The expectation is that they may lose it all and it was a gift, but there is the possibility the investment could do well, and you will gladly repay the favor.

I'm hoping they can help me get a shoe in on a smaller deal with someone whom they've worked with in the past and that will help me get a great deal with less favorable terms.