To add additional children the help says "on the account page, click account preferences" but I do not see an account page. When I sign in to powerschool, it opens directly to the daughters page with all her info. There is no other tab along the navigation bar, that I can see, that gives me access to my account info.
You would need to scroll down under Class registration, there should be "Balance", "My Schedule", "School Information", and finally "Account Preferences".
In case, you still continue facing any issues, we recommend reaching out to your district for further assistance.
Scroll down to the bottom of the left side of the screen. See the attached screenshots.