You need a separate forum account AND game account for each person. If you try to make a second game account on the same forum account, it won't work. You need to log off the forums, make a new forum account for your daughter, then log into that new forum account and make a new game account for her. The system uses BOTH accounts, and they have to match exactly.
This, the forum account and game account are separate BUT they are linked to one another, so each game account needs its own forum account.
Each new account to play the game you must:
Make a new forum account then click the "game account" thread to make your actual game account.
This link the forum and game accounts.