BTW, asking or telling him NOT to use D18 appears to be making him dig in, or at the least, he's just not going to listen to that.
So it is up to you to figure out how without telling him. As that was one of his complaints, wasn't it?
Like I said, and this is very DB... Change the sitch. Start DOING as a responsible adult and parent and eventually, he is likely to do the same. He can't keep doing the same thing if you change.
