Hi,
I haven't sent off my husband's inland application yet, so this is just my take on your situation from what I've read and prepped so far.
At the top of 5556 it states that "this document is one of the forms that you need to submit with your application." Have you already sent your application? I would see if there's someone you can call to get a definite answer. If not, in that situation I would personally print off another application and resend it just to be safe, as it states in the checklist that any missed documents will result in your application being returned to you.
If anyone else has some info it could definitely be helpful to get another perspective on this. Best of luck to you!