[Zubersoft]

Although it's too late to help now, if you are going to swap out something like that and want to keep all the annotations, your best bet is just to manually replace the image file being used by MobileSheets (in the song editor, tap and hold on the file to see an option to display the full path).

Ultimately, I should provide users with the option to swap out image files and maintain annotations, just like I do for a PDF file.