Neighbour

A merged document has no numbering of its own

Three files became one, and the page numbers now run 1, 2, 3, 1, 2, 1, 2, 3, 4 — or stop entirely.

That matters the moment anyone has to refer to a page in a meeting. Adding numbers across the assembled document gives everyone the same reference, which is the entire function.

It is the same kind of edit as a watermark: something added on top of pages that already exist, applied across the whole document at once, and recorded in the file rather than in the viewer.