While I'm not a legal professional, here are some general considerations that might help guide your decision:If there are any legal problems pertaining to the property, an LLC might offer an additional degree of protection for your personal assets.

@Ayyoub Reza   There are a number of places to get agreements but make sure you get one that is current and state specific (here, legal zoom, a lawyer, real estate association ) Read your HOA bylaws what does it require to be included.

Look for better deals to provide latitude to deal with unforeseen issues.

To change batteries remove the screw.  2 years with no issues.

My primary issue is the value added by the ADU versus the cost.  

Maybe I am having a Google issue or something, but when I search for these, I am not confident in what I am finding as being what I am looking for.

But in absence of a SSN, whatever legal action we take mag not result in any meaningful recourse. 

If you are considering MFH in San Diego, hopefully (1) you are working with an astute agent who has or can address these issues. 

Mistakes in real estate cost real money and lead to a lot of problems, sometimes legal. 

Once you have a handful of units, things become more stable because you gain a lot of experience and also when issues arise at one unit, the other units still carry the expenses.