Navigate to the family record screen, select the more menu from the child tab. Then select the contacts option.
To add a new contact click the add new contact link-
Then scroll to the empty contact information fields. Be sure to select Yes from the payer? drop down menu. Complete the record- including email address then press save.
To edit an existing contact click the edit icon-
Under payer information, select Yes- then press save.
After pressing save, the user ID and password will automatically be set. Provide this to the contact or the parent to allow the new paying contact to login.
By default the payer will be added to the system with the Family Portal Contacts (Not Allowed) role on the setup > admins, actions > setup roles area.