Hello Sjef. All of us here at BC would like to welcome you to our great site.
I know how it is with teenagers. You could always get one of those vending type safes that would require a deposit of $$$ to be able to use the computer and have it set for a particular amount of time. Well, it worked on The Brady Bunch with the phone,
. Anyway, make yourself at home and please don't hesitate to ask questions. We're always happy to help.