Location 1: FMS serves files (eg. customers.fp5, quotes.fp5, etc) to the local FM network.

Location 2: FMP 6 shares files (eg. w_customers.fp5, w_quotes.fp5, etc) with the local FM network.

Both sets of files are virtually identical.

Every day Location 1 files are updated via import scripts with Location 2 data.

A key relationship used in the updating process is quotes::id = w_quotes::id

The other day the DSL connection failed just before the import script was run. The connection is up again, but the script does not work properly because the key relationship now reads quotes::id = quotes::id

It seems to me that because FM could not find w_quotes.fp5, it settles for quotes.fp5 instead.

I know FMP 7 does a better job with this, but can anyone advise me how to prevent this happening in the future?

If your script doesn't begin with the Set Error Capture[on] step, you should add it in. This will often prevent the problem of file references getting changed if the file can't be found.