John O'L you say, "Our biggest problem is that she is 12 and he is 9. He thinks he's ready for whatever she's ready for."

A twelve year old should have more privileges than a nine year old. Of course those priviliges should be accompanied by more responsibility.

I think its time for the 'little talk' about the difference between wants and needs. Then you can go on to talk about how, at different ages, you earn privileges with responsible behaviour.