You can force a custom number for a page using a special note: [[page pageNumber]], for example [[page 3A]].
Add the note on any printing element (so not to sections or synopses) or have it sit alone on a line. The page where it happens to sit will now get the custom page number.
You can combine forced page breaks and forced page numbers to create appendix pages or insert new scenes to the screenplay while still keeping other pages and page numbers intact. Following pages will continue where the page count was left off before the custom number.
