You can use INCLUDETEXT fields to bring in content from several individual files into a "parent" document. After you have edited an individual file, you can update the "parent" document by selecting the INCLUDETEXT fields and pressing F9. Conversely, you can save changes made in the field result back to the referenced file via Ctrl+Shift+F7.
You'll find more information on INCLUDETEXT in the article at
http://word.mvps.org/faqs/tblsfldsfm...textfields.htm, but note that this articled may not be updated for recent versions of Word.
To insert an INCLUDETEXT field, you use the Insert as Link command in the Insert File dialog box. To display the dialog box in Word 2007 or later, click the Insert tab, click the arrow on the Object button, and finally click Text from File.