@Paul LaSpina Obviously consult with your attorney/CPA, but if there are only 2 parties you'll waste a lot of money, time and resources going the syndication (GP/LP) route. 

  $89k,  borrowed 80%, payment was $616 and collected $525 in rent from other unit. 

I will definitely use you as resources....

But someone who is syndicating funds and collecting other people's money should have a LOT of experience in real estate investing and know what they're doing. 

We decided to partner with our mom in law real estate investing because she was retired, had plenty of cash, collected on her husband's life insurance, and frugal all her life.

BP is an excellent resource for great information and an every greater group of other people anxious to help you.

Also, will I be able to sue the squatter for the back rent that I could have collected and damage caused to the property and HOA fees for them living there?

We handle everything from marketing, screening tenants, providing/executing leases, rent collection, maintenance coordination, walkthroughs, etc. 

If your payment after collecting one unit of rent is less than renting the equivalent unit then all is good because see item 2.  2) You get to write off the interest related to your living unit.  3) Markets fluctuate in value but San Diego historically has always risen over enough time. 

I found Bigger Pockets 2 years ago but im shy and it took me a while to get engaged and realize that were all just students of the game of real estate and some are farther along their journey than others and that is no excuse for me NOT to network and get to know many of you on here and tap into everyone's experience and knowledge and resources to build up my rental portfolio and to help others along the way as my knowledge and experience grows over time.