After you file

Yes.  I'm sorry I wasn't clearer.  I amended my wording slightly to say to "attaching a statement to each tax return".  When you do the amendment, you will need to type the reason for the amendment into the software.  I'm not sure how closely those are looked at, however.  I suggest typing a general note that explains the situation and which years are being amended.  Then,  placing that same note in each envelope so they know that you will be amending multiple years if they start to process a later year first.