If you cannot add more pages to it - cannot test it right now, but quite likely that you might not be able to - then what about using Preview over in the Mac to create a PDF of that line-design, but with 3/5/10 pages?
You could then import it, having saved the 'original' in Documents/Goodreader (or something similar) on your iPad - and use it that way. Maybe save a 3, 5, 10 and 20 template - that way you can simply import the version you need into Notability, and delete any pages not used when you are done?
Just a suggestion. Clunky, but could work.