Is Binder a Mac-specific term?

In short, there isn't a simple way but you could do something with fiddly nested fields and set starting numbers for use in those nested fields.

If I was doing this on a Windows version of Word, I would make the Word docs as per normal with 1/20 page numbers. Then I would print them all to PDF and 'bind' them into a single PDF. Then I would use a PDF editor to add page numbers with the combined page numbering.

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Andrew Lockton
Chrysalis Design, Melbourne Australia