Look into renting by the room (check occupancy limits for unrelated adults) if this doesn't pan out.

The young adults give me hope for our future.

My pregnant niece (17 years old) and her boyfriend (18) put down a deposit on an apartment without "adult" input.

I charge $20 per adult.

Set policies, put them in writing, commit them to memory, and do not waive them:All adults must pass your screening;Nobody moves in without proof utility accounts are established, rent and deposit are paid in full;Rent is due on or before the 1st, period.Late fee is applied on day X, period.3-day Notice to Pay or Quit is filed on day X, period.Eviction filing (forcible entry and detainer) is filed on day X, period.Be prepared to handle lease violations (unauthorized pets or tenants, vehicle parked on lawn, not mowing grass, etc.)A little education and preparation will go a long way.

This sweet, hard working adult man, literally cried tears while I helped him complete my application.

All of them can just go...uh, hmm, I can't say that in a family-friendly forum.Anyway, that's what's worked for me consistently in my adult life.

In the future I would definitely recommend adding a clause to your lease that all occupants must be disclosed and adults must be added to the lease. 

It is an organization that I've run with since 2009 pushing kids and adults with special needs marathons.  

@Gary Lansford I mentor a few young adults and you my friend are the exact person suited to buy a duplex for their 1st property.