It does sound like both boys are headed in a scary direction. Because it's illegal for them to skip school, you must report to their schools every day that they do not have your permission to be absent and are truant. Another person you should report to is your son's diversion officer. Report any new wrongdoings or noncompliance with diversion to the officer, and discuss what happens if he is kicked out of diversion. Will he go to court? Will he be issued a probation officer?
In Nebraska, parents are expected to provide the basic needs for their children until they reach the age of 19. So, even though your son is staying at a friend's home, you would still be accountable for his behavior, and it's nearly impossible to monitor his behavior when he is not living in your home.
You are spot on—your children need some help. Some things you can do at home are, again, to report truancies; conduct room, car, and pocket searches and report any drugs or paraphernalia to police; and put all medications (even those prescribed to them) under lock and key. Each time your 15-year-old leaves the home without permission, report him as a runaway. This is as much for your protection as it is protection for your son's.
Kids are placed at Boys Town privately by parents, through the court system, or through social services. Most children who live at Boys Town have tried a variety of other services that have failed. If you're interested in looking into private placement, please visit boystownadmissions.org for a review of the program, a video presentation, and initial paperwork to fill out. Youth who attend are ages 10 to 17. Youth who are privately placed must agree to the placement, as it is not a locked facility.
In order to determine the level of care your sons would need for their substance abuse, a substance abuse evaluation would need to be conducted to determine the level of care needed. Please give the Boys Town National Hotline a call if you would like a crisis counselor to look up some referrals for you in your area. We would be happy to assist. You can also contact the Nebraska Family Helpline (1-888-866-8660), which assists parents in the state of Nebraska when their children are struggling with behaviors.