Multiple Pages in a Collection

I know you can specify multiple taxonomies for a collection, but can this be done for pages as well? Or can multiple collections, each with one page, be specified? I haven’t been able to find a format that works. But it would basically be like:

@page.descendants’: /page1, /page2, /page3

and show descendants of any of these pages (comma functions as OR).

Currently pages only takes a singular page. Perhaps suggest this is a future feature: