[ronpietrantoni]

Don't remember the exact wording, but I've always done this sort of editing from within Page Rearranging - where you see thumbnails of all the pages. I would scroll to where I wanted to insert the new pages, tap the three dots, navigate to the desired insert and it would just work. Until today. Both files worked fine individually. I actually finally solved it - but it will finish making me mental if I have to do this every time: I reversed it. Opened the two-page file and tried to add the 100+ pages of the original. THAT worked just fine. So I backed out of it without saving and tired ONE more time to do it the proper way - and then it worked.