- How do I convince my parent's I'm not gambling my savings?

In terms of debts, I agree with @JoeHammel - A title company is the best resource to check on all liens which could be contractor, IRS, bankruptcy, local utility bills or property tax, child support, etc. 

The ADU is meant for a parent at the present, but it may be rented out in the future.

Especially if you are now living with your parents.

I grew up with parents who did realestate, own a few properties and help manage a commercial property. 

. - But I have a family member (Brother or Parent etc...) who is interested in putting some money into it.- Total start up costs (Down payment + closing costs, furnishing, getting started on Airbnb etc...) = 200k USD- Family member wants to put in 50k USD of the start up costs, but doesn't want to be on the hook for the mortgage. 

My parents worked 5 jobs, FIVE.

From my 6 years of living in USA, my observation, I have realized that in American norms, parents' well-being in not their kids' responsibility.

In the middle of a sale of my parents condo and it's been 5 months and we have not closed due to title companie's lack of communication, instruction and then bringing an outside attorney into the fold to assist that has dragged this on even further.

I would think she’s to receive child support payments of a fairly significant amount.