Allow a page to live within two projects

Would love the ability to have a single page live within two files. Sometimes I have a page with items where they could potentially live in a few different files. Right now, I’m just using a widget to link to the other pages, but would love if a page could sync across multiple files. Kind of reminds me of how instead of folders in Gmail, you use tags, so you can tag a single email with multiple relevant tags. I want something like this for pages.