If the application only involved one adult (any children?)

Large children (and adults) are capable of punching holes in walls, and equally not caring about your unit in general.  

I own an Adult Family Home in Kent, Wa.

Have all the adults sign the lease so they all have skin in the game.Or just flat out NO.

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? 

Technical schools can attract a lot of returning adults, they can have non-traditional scheduling. 

According to the National Association of Realtors (NAR), 17% of homebuyers purchase a home to share with parents, adult children, or extended family.

🙂Im 45 years old, not married with 3 adult children who live with me.

Future reference: if it takes 3 unrelated persons to pay rent and security, and/or if these tenants are students or otherwise just starting out, having them jointly and severally responsible is just the start: get the parents/guardians or some other 'established' and related adult to co-sign the lease.This info is based on my personal experience.  

We need to speak to each other like adults, not like high school kids, which means face to face.