Your attached file is the same knownSeriesIds file you provided before. I did include it in the T4 distribution. However when MG3 merges the distroSeriesids file with your local existing knownSeriesIds file, it gives precedence to the local file, thus it will not replace a local value with a distributed value. Which file should get precedence depends on what the relative probability of errors are for the two files. If we give the distributed file precedence, a user could have decided a distributed item was incorrect and replaced it locally, but unless the correction was made in the distributed file, the correct local value will be overwritten by the incorrect distributed value each time a new version of MG3 is run. So, do you think the precedence should be switched to the distributed file? I'm OK with either way. In the case that an incorrect item exists in the local file, but no item for that title exists in the distro file, the incorrect item will not be purged -- a merge is being done. To reverse that behavior means you're just replacing the entire local file with the distributed file. I think purging local items that aren't in the distributed file is likely to be very upsetting to some users, who have added items beyond those that were distributed. I think it will have to be the users responsibility to purge such items (or correct them).