I'll preface this by saying I've already taken these questions to three separate professional accountants. 

Currently there are 3 buildings with 3 separate checkbooks.

Single Family Renovating too be used as a 2 unit with separate mother-in-law suite unit.

Has full separate entrances5.

As a person with extensive use experience of such, I will say at worst would take maybe as much as 1hr to track an heir, emphasis on "an" as the correct tool in this arena, or more specifically the one I used, I could dig up the last 30 years of a persons history, every address, co-habitant, everyone in 1 degree of separation, there 30yr residency/ work. sphere and so on and so fourth. 

However, if its a JADU then it would not require a separate garage.

In my state the reason deposits are held in escrow accounts is so a neutral third party has the money in the event of a conflict like you are describing.Your first mistake was to get into a hurry: I could be completely wrong but it sounds like you made a hasty decision based on emotion and not on what may have been best for your situation.

I guess I also need separate meters/boxes.

Hi BP,I've been looking into real-estate investing for awhile now and I'm at the point where I am going to be making a purchase.My question is: I am newly engaged and wondering, with the thought of buying homes in the...

Those separate loans cost ~1300/month.