The way I'd do it - use IBexpert or a similar tool to export the data from the table in question from both databases as INSERT statements, and then compare the scripts (winmerge or similar), isolate the differences and use the script to update the database.
It becomes a bit trickier if you have auto-generated keys in that table, as you will probably have to omit the auto-generated field in the script, which will generate new values, and then even trickier if these are foreign keys somewhere else. There might be tool to do this automatically, but I don't know, Good luck :)
