When you log into the parent portal, you should see an Account Preferences icon. Click on the icon. You will see your profile page. In the tab next to profile there is one called Student. Click on that and then the add button. You will need the account ID and password to add the other students.
If your PowerSchool district is configured to allow you to add students, you may do so via the PowerSchool public portal using a web browser.
I hope this helps, feel free to reach out to us if you have any further queries.
@Tyr123 You will then need to contact your school and/or district. They may have customized the page and blocked the icon for showing. Unfortunately they are the only ones who can help you at this point.