That could also leave Dave in a legal bind ~ you've approached to make the purchase. It doesn't matter that the money comes from elsewhere. The best way forward might be to get your Dad to make contact with Dave through his website (in his sig link at the bottom of all his posts).
It's unfortunate, but it doesn't matter how mature or responsible you are, you're under 18 and trying to buy a knife from Dave (irrespective of parental knowledge and / or approval) could land Dave with (expensive) legal issues.
I hope you do get sorted ~ he makes some cracking stuff

(including my EDC)