We've had success with creating robust Word docs from FileMaker data only by using the 360Works Scribe plugin. It's not a native feature of FileMaker.
using applescript from within a filemaker script it is possible to open a word document - then insert a field contents at a bookmarks in the document & then save the document - the applescript for MS Word is not transparent but can be done e.g.
set variable $Applescript as:
"tell application \"Microsoft Word\" " & "¶" &
"select bookmark \"Name of Bookmark in the Word Document\" of active document" & "¶" &
"type text selection text " & "\""& $TextInFieldToBeEnteredAtBookmark & "\"" & "¶" &
perform applescript $Applescript
360Works Scribe works elegant for your case. I have used it in several projects and it comes with very good example databases.