After an order has been sent to the IRS/SSA for filing, the forms in that order can’t be modified (corrected) until the IRS/SSA has completed processing the file. If you’ve already placed your order, wait until you receive an email notification that your order has been accepted or rejected by the IRS/SSA.
When you’re checking out you can use eFileMyForms’ Delayed Processing Options to delay filing to a selected future date. In between placing an order and your delayed processing date you are free to edit the forms in your order.
Read our article How to resubmit rejected forms for information on how to edit forms after they’ve been rejected by the IRS and submit them again.