How to: Add an existing document to a master document in Word.
Solution:
Display the master document in Master Document view and click 'Insert Subdocument'. Select the filename to be inserted.
1) Open the master document.
2) Select the 'View' menu and select 'Master Document'.
3) Position the insertion point where the document is to be inserted.
NOTE: Do not insert into another subdocument.
4) Click 'Insert Subdocument' on the Master Document toolbar.
Insert Subdocument button
5) Select the document from the 'File Name' list box.
6) Click 'OK'.
7) Repeat steps 3-6 for each document to be inserted.
8) Select the 'File' menu and select 'Save' to save the master document.