If you value your work,
don't use Master Documents. See:
http://word.mvps.org/FAQs/General/Wh...ocsCorrupt.htm
http://word.mvps.org/FAQs/General/RecoverMasterDocs.htm
http://www.addbalance.com/word/masterdocuments.htm
FWIW, there's little the Master Documents 'feature' provides that you can't achieve through the use of a properly configured template for the document set, combined with the use of INCLUDETEXT & RD fields for whatever linking might be required.