My client wrote a book. Each chapter is a separate document with endnotes at
end of each chapter. Publisher wants all endnotes at end of book, not end of
each chapter. This was not set up as a master document. Is there a way to
move chapter endnotes to a separate document for all endnotes, keeping the
automatically numbered endnote numbers within the individual chapters? Would
making this a "master document" be of benefit? Any suggestions?

I use Word 2003.