How to Insert and Remove Pages in a Book
Adding a Page Where You Need It
While editing a book, navigate to the page next to where you want the new one. Scribble adds insert and remove page buttons to the book interface. Use the insert button to add a blank page at the current position; the pages after it shift down so nothing is overwritten. This lets you drop a new section into the middle of an existing book instead of only appending at the end. Fill the new page as normal, then continue editing.
Deleting Unwanted Pages
To remove a page, go to that page and press the remove page button. The page is deleted and the following pages move up to fill the gap. If you delete the wrong page, use the undo shortcut to restore it before saving. Keep an eye on the total page count, since books have a maximum size; inserting pages when you are already at the limit will not work, so remove something first. When you are happy with the layout, save the book. The mod ensures your progress is saved before you exit if there are unsaved changes.