Can I change registration info on only one device of several linked to my iTunes account?

I have 2 iPhone 3Gs and a new iPod touch all linked to my iTunes account. I know when we registered the iPhones, my wife and I each used our own names but all other info on the registrations were identical. No problems. We bought the iPod Touch 4th generation for my 12 year old, but I made the mistake of leaving my own name in the registration for it. Now he gets all the same texts that I receive on my iPhone and he can not text my iPhone. When he texts my wife's iPhone, it shows up as a text from me, as if it were from my iPhone. Is there a way to either change the registration on the iPod Touch or unregister/reregister it so that he doesn't get my texts? Some of our texts are definately not age appropriate for him and I would like to be able to text him while I'm out and about to check on him. Thanks in advance...