Can I save a Master document in a .docx format

In Can I save a Master document in a .docx format? My publisher cannot open a .odm file I have seen a similar question.

What I would like to do is export all document content in one large .docx document, and a reviewer can add comments. So I can see these comments, on the correct position, and correct them.
The original response was:

Saving as .doc(x) will make it an ordinary document, losing all properties of a master.

That is okay for me.

But I can not save mydocument.odm as mydocument.docx. Trying to do so results in mydocument.docx.odm which is still a .odm file.

This must be done in two steps.

  1. File>Export to create an ODF document (.odt extension)

    Make sure you select to correct document type.

  2. Open the .odt resulting from the previous step and File>Save as, choosing either .doc or .docx output type.

Warning! The subdocuments are converted to sections by the first step. These sections keep the protection attributes of the slave documents. By default, they are write-protected, so are the sections. If you want to make them editable, clear the write-protect attribute before exporting to .doc(x).

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Thanks ajiltoz, this does work for me.