You have two basic methods of doing version upgrades to the backend
MDB.

1) Ship a new empty MDB and copy the tables across in relational
sequence, ie parent records, then child tables and so forth down and
across the "relational tree:"   This can be done by creating a table
containing the table names with a relational sequence field and
running down the tables doing append queries.

Where appropriate you will need to copy specific fields to other
tables to split data out given new tables.

2) Create a bunch of code within your new version which creates the
new tables, relationships and new fields on existing tables.  Then
copy the records across from old versions of tables to the new
versions and delete the superfluous fields.  

Updating an Access Backend MDBs structure using VBA code
http://www.granite.ab.ca/access/backendupdate.htm
(Note that this page will be updated in a few days with new code.)

Neither process is simple.

In both cases I would suggest keeping a version number of the FE and
BE in a table or property thus helping you to figure out when to run
the code or not allow a new FE to be run against an old format BE.

Also make a backup before doing any such updates, double check the
number of records in the new tables after the conversion and include a
mechanism to ensure users aren't in the backend when all this starts
or during the process.

Clearly this is not going to be a simple task.  <smile>

Tony
--
Tony Toews, Microsoft Access MVP
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