Reply To: Automatic section numbering

You can’t get there using a master page and what’s baked into InDesign.

A custom numbered list, however, started on a regular page, can be extended using “Duplicate Spread” from the context menu in the Pages panel. In the list options, be sure that you select “Continue numbering across stories” is checked. The frame you place on your “pseudo-master” can contain any kind of non-printing character, such as a thin space or hair space. All the list function needs is some kind of content, at which point it obediently provides a number.

As the document is being edited, if the order in which these created pages changes relative to one another, the numbers in the frames will change so that they remain consecutive in the document.