[Zubersoft]

MobileSheetsPro does not currently support an easy way to merge PDFs. This is something I do plan on adding at some point. There is a way to accomplish this though, but it's tedious. If you go to the library screen, long press the song and select Share->Export Files, and then check the option to join files, you can create one PDF from all of the files in the song. You can then edit the song, remove the other files and add the single file with all pages. 

It's always better to produce one PDF at the start if possible. Did your scanner generate one PDF per page?

Mike