(I would question it since the main home is not renovated) what are the chances that they did everything right on the ADU but didn't have the funds to do the home… hmmmm doubtful Make sure they have the permits (call the city and see if they have permits on file). 

Send them notice of balance due, file collections, and sue them in small claims court. 

Well, when it comes to filing taxes I usually don't rely on the kindness of strangers (especially when they have no liability), but if you think getting a lot of replies (some conflicting) will help you make up your mind - Have at it.Honestly, am not trying to be a jerk (as you can see it comes naturally), but your tax guy is the best liability shield against the IRS you have. 

There are also additional costs of operating and maintaining an LLC, like separate bank accounts, annual report filings, tax filings, etc.2.

It looks like I will be able to file a lawsuit in my Texas county instead of theirs because they do regular business in Texas by selling their products via a sales rep who solicit business by phone and email. 

I am seeking recommendations for a Registered Agent to handle LLC setup and related filings for new real estate investment business that my partner and I would like to set up. 

Anyone can sue anybody in America, it takes few bucks in a district court to file a piece of paper with clerk of the court.

This is generally done through, a quitclaim deed or warranty deed, filed at your local county recorder's office.

Many counties have exemptions that can be filed so it will vary most likely on your situation (primary home v investment), senior, disabled, etc on what those exemptions may be.~ Lindsey

All rental agencies have to keep these numbers on file.