Do you need all adults to sign?
I'm renting out my 2nd home to three adults, but only one is working. The other two is the mother and her adult son who's 25, but I guess going to school so should I have all three sign.
at the very least, you should run background checks on each person if they are over 18.
i really think everyone should sign so its clear they all agree to your terms, but i would understand if you just have the one who's working sign. the more, the better though especially if the son is 25.