Absolutely! Quite a few of our Teen members also have DIS parents. And we have DIS spouses that also have their own accounts. You will just need to logout of your account and start a new one. It can be kind of tricky. You may need to clear your cookies. You will also need a separate email account for the new account.
I have found that sometimes my computer gets confused and I will be on one account but when I go to post it dumps me out and logs me in and posts as the other person. It is definitely easier if you have 2 computers.
One warning though. If one user is banned for not following the DIS posting rules then often all members of the household are banned also. So just be aware that you need to monitor your daughter and make sure she fully understands the posting rules. You can find the guidelines here:
http://www.wdwinfo.com/guidelines.htm Let me know if you have any problems or you can post on our Tech Support down at the bottom of the main page. They are quite a bit more tech savvy than I am. My answer to everything is just "toss your cookies"!