Dealing with change.

I'm writing an application that depends heavily on "reference" tables that
the user can use the select data from.  The users should be able to add to
these tables and make any corrections they deem necessary.  But I also want
to be able to periodically ship out corrections and additions to these
reference tables.  What is the best way to do this without interfering with
the changes the user has made?  I thought of keeping the reference data in
its own database and using this as a template for the user database, but how
would the user merge any changes to the template (or would this be
automatic?)

Thanks for any advice you could give me,
Dave Cook