If I understand your description correctly, the two companies have documents with common content but different front matter. For such a situation, the simplest approach might be to create the stand-alone body document and for the users in each company to use an INCLUDETEXT field pointing to that document wherever it is stored on their system. An equally viable solution might be to embed an INCLUDETEXT field in the stand-alone body document that points to a file that contains the front matter. The documents containing the front matter for each company, though different, would have to be saved with the same filename. If the path on each system to that document is the same, that's all that would be needed; if not, you'd need to modify the INCLUDETEXT field in the stand-alone body document to use relative file paths, as per the field code solution I've posted at:
http://windowssecrets.com/forums/sho...External-Files