Thank you for the detailed information, Papet!
I wasn't able to find the dialog box in step 3, which may be because I'm using the browser version, not the PC software. But I was able to find a PDF version called 'Federal' which has all the sheets you mentioned, The one oddity was that the page 3 of the condensed T1 was listed as 'Page 8 of 8,' although it only included pages 1 and 2 before it. I assume this is the page 3 you listed, but the PDF is confusing. Hopefully it's not missing anything.
I also noticed on the page 3/8 which begins with 'Step 6', the box labeled 'Refund of balance owing' is left completely blank. She doesn't owe anything, but I'd assume Ufile should put a zero in there? Or maybe the CRA just assumes a blank box = 0?
Thank you again for all your help, you've been a godsend!