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ClairePMR - if you can find a one-click way to merge the subdocuments within a Word master document into a new single document that maybe preferable, then you could maintain the separate chapter subdocuments as the manuscript form. I've looked and failed to find, but that doesn't mean it doesn't exist - maybe in Word itself
A Word master document is not unlike an ePub OPF file, basically a playlist. Unfortunately Calibre cannot convert Word master documents, be good if it could.
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