You can add and edit payments after the payment schedule is published and after parents have signed up.
If you want to add/edit payments for the entire team, go to the team page. Click 'View Payment Schedule' then click 'Put Payment Schedule in Edit Mode'. Click 'Edit Payment Schedule'. You can now add and delete payments for the entire team. Parents who have already signed up will receive email alerts for changed payments. If a payment is added, they will be asked to approve it before they are billed. Note: if any team payment has already been paid by someone on the team, you can't delete it from this menu. After you're finished, re-publish the payment schedule.
If you want to edit payments on a per-player basis, go to the player page. You can edit payment amounts or delete the payment by clicking the 'Action' button to the right of each payment in the payment table and selecting the appropriate action. You can also add a payment to only this player by clicking the 'Add Payment' button.