Change my last name?

Hey all,
A while back my parents got married and my last name was legally changed. My school at the time (elementary) kept it at my old last name. And then that carried over to my middle school, and then my high school, ect ect. But lately (well, a year back) I've been using my legal last name for work, state tests, ect. Up until then, I was just using my old last name because that's how my friends/teachers knew me. Now in an effort to change my last name from my old one to my legal one in the school records, it hit me. My WoW accounts. I've been a bit lazy to change it but I figured I should ask now.

Is it possible to change my last name to my legal one?

Before my account had a fake name (Derek something I think) because my mum's identity was being stolen at the time and I was a bit sketchy. But when I was on the phone to fix my game time, they fixed my name. (I figure it has to do with the credit card?) My second account still has a fake name, but I haven't put in any efforts to fix it (paying it through phone).

So, what do I need to do in order to get it fixed? Scan a picture of my ID w/ a picture of me or what? It's just my last name, not the first (unless I have to fix the second one as well. I like the America/Chinese mix I put into it, but if I have to)

Thanks =D