CF or not he is 16. My Father used to say when he was 16 his parents were stupid and by the time he was 20, he was amazed as too how much they learned in four years. All that you can do is wait it out.
My parents were lucky in that I didn't do the stereotypical teen rebelling, but very unlucky because I did the CF rebelling. They let me do things my way so I could see the consequences. I know that sitting back and watching me harm myself by not doing treatments was one of the hardest things for them to do, but I'm grateful they did it.
Before my rebelling period, I understood the disease and its consequences. After I got back on track, I respected the disease and that has made a huge difference in how I take care of myself.
thank you for that honesty! It's very hard and I didn't expect it to happen, which leads to some guilt. But you have given me some hope!