efficient solution to using a master file?

Hi,
I am programming an excel template (BookA) used as sort of like a database, thus there could be lots of files like these. But all BookA files refer to one master file (BookB) in a shared drive for fetching data and drop-down lists (i.e. using validation list). Currently, I have the procedure as follows.
-Open BookA
-BookB opens automatically from WorkbookOpen event, and hides itself in the background
-BookA users can use drop-downs and fetch data via buttons
-If BookB closes, and BookA remains open, Everything crashes.
-When BookA is closed, BookB is closed automatically from WorkbookClose event

Is there a more efficienct solution to this?

I thought of:
1) When BookA opens, open BookB and copy ALL data to BookA, which is about 10 sheets, when BookA closes, close BookB. This seems like a very slow procedure everytime you open the workbook.
2)Somehow copy all defined ranges from BookB while its closed and use them for BookA. dont know how?

Any response is appreciated. Thanks

I used FileCopy command on workbookopen event to copy the master file into C: drive, so everyone reference their own copy, but get the latest copy from shared drive
Works like a charm!