Your described requirement makes it sound like you are delivering the file to end users who plan on using the Navigation Pane to get around. The number of Word users who do this is only a very small percentage of the total number of users so it is hardly worth getting wrapped around the axle over this issue.

However if you actually deliver the file as a PDF, you can rename the bookmarks (Acrobat's term for what Word calls the entries in the Navigation Pane) to not necessarily match the headings on the page. Acrobat users are far more likely to navigate the document with the bookmarks pane showing and this is a much better format for a group of users who are outside your organisation because you don't know what versions of software they have.

__________________
Andrew Lockton
Chrysalis Design, Melbourne Australia