The attorney is not technically needed however most buyers will not want to pay off the seller's underlying debt and just assume that everyone is honest enough to provide title in the near future when things are satisfied and clear title is able to be transferred.

A bit of background I am based in San Francisco and have been investing in multifamily C class assets in Columbus, OH for the last three years.

@John Feldhauser, technically it follows the same procedure regardless if a rental or owner occupied. 

Background/credit check, income verification, talk to their boss, talk to their last two landlords, collect a security deposit, etc. 2.)

A bit of background - I bought 2 properties out of state using hard money loans last year.

Since he isn't technically a tenant, do tenant laws apply to him or is he simply trespassing at this point?

It would be easy for me to say that you should focus on credit score, employment check, background check, etc., but there is nothing that really beats the experience of working with someone who has done this in the past and learning from that individual.  

Maybe ask them to sign an amendment to the lease adding that person so you can do a background and credit check.

My husband and I have 20 doors so far which is great but I have no background what so ever on how to do bookkeeping, finances, excel, etc.

Technically that is what this is supposed to cover.Security Deposit:  How much security deposit did you get?