At closing, one tenant moved out as part of the agreement, and the other tenant (a single adult who had been living there for about 1 year and 5 months) stayed.

Do they require each adult that will be renting to complete their own application?

I have two adult kids.

We have had the same situation both at an existing house and we even built a brand new house for a group home for mentally challenged adults. 

Trump was convicted in NY state supreme court on 34 counts of falsifying business records to conceal a hush payment to adult film star Stormy Daniels ahead of the 2016 election in exchange for her silence about an alleged sexual encounter.

A quick call to a past landlord can tell you a lot.All adults should be on the lease and responsible for rent and damages.

But in general answer to your question (I'm in North Carolina, not South) - I have a provision in my lease that ALL person's age 18 or above (at the time of lease start or renewal) must have an application on file, that includes credit and criminal / background - and I have the right to an updated credit and background report from all adult residents prior to lease renewal.

Most adults can't get past this, and it's extra hard as a kid in a school where you're stuck seeing the same people every day, so don't expect to just change your mindset in 1 day, this is something everyone struggles with.

And - if you're going to provide seller carry financing, is there anyone in your life or circle that you are familiar with looking for a great deal and their first 'adult' investment/purchase? 

There was a TV show on Netflix or Prime I believe about how to build an adult play room.