To understand why MobileSheetsPro doesn't currently support that, it's important to know that annotations are stored based on a page number. This page number is not the page number in the file itself, it's the instance of the page in the page order. This is important so that you can have multiple instances of a page (i.e. "1,1" would be page 1 twice) but each instance of the page can have different annotations on it. If the annotations were stored relative to the file itself, then it would not be possible to have different annotations for each instance of a page.
So knowing that, if you removed the first page of a song, for example, this would cause all of the annotations that were previously linked to page 2 to become linked to page 1. MobileSheetsPro then no longer has a valid page for the annotations for the page instance that was removed, so it deletes them from the database. If you put "1" at the end of the song/piece page order, then it would preserve the annotations (i.e. if the page order was 1-10, you could do 2-10,1).
If you want to be able to add and remove pages frequently without this affecting the annotations at all, then you will need to embed the annotations in the file itself, and you can't have multiple instances of a page with different annotations on it. To embed the annotations, open the annotation editor, tap the three dots at the top right and select "Embed Annotations". This will allow you to save the annotations in the file. Note that you will not be able to edit the embedded annotations unless you enable "Allow editing of embedded PDF annotations", but enabling that option has a few consequences, namely:
- PDFs will have to be reopened in a writable mode when the annotation mode is entered which can cause a short delay if the PDF doesn't load quickly
- Editing an embedded PDF will cause annotations to be saved back to the file which can slow down the saving a little bit (depends on the PDF and the file I/O)
- Once annotations are embedded, you lose some of the editing options (what you can or can't do depends on the annotation type)
I used to provide an option to automatically save all annotations in the underlying PDF, but users were enabling the option without understanding the consequences, and then I had to deal with complex support problems that took up a lot of time. So I removed the option and users have to manually embed when they are confident that they need to do so.
Mike
