Incidentally, I had a related enhancement on my to-do list for the 5.1.12 release.
Since IMatch now has a 'database' of which file formats take embedded XMP metadata (or for which file formats the user explicitly forces IMatch to use external XMP metadata) I thought I can use this data to handle XMP files a bit smarter when moving/copying/renaming/deleting files.
So far the "XMP belongs to all files with the same name in the folder" was always enforced. If you have a folder with a A.RAW A.XMP and A.JPG and you copy the A.JPG to another folder, IMatch always copies the XMP as well. The same rule is applied when you delete the A.RAW. Since there is still a A.JPG in the same folder, the A.XMP is not deleted. When the A.RAW is renamed, IMatch actually duplicates the XMP file so we end up with NEW.RAW NEW.XMP A.JPG and A.XMP.
For IMatch 5.1.12 I have changed this behavior. IMatch now uses the per-file format XMP settings database to determine if a file that is copied, moved, renamed or deleted actually requires an external XMP file. If this is not the case, existing XMP files are ignored. If you now copy the JPEG to another folder, the XMP file is not copied. If you rename the JPEG and XMP file with the same name is not renamed.
If a user enforces IMatch to use XMP sidecar files also for JPEG files (not recommended) the old behavior kicks in and IMatch keeps the JPEG and the XMP together as before.
I'm, not sure if I should just implement this, or add (yet another) option to allow users to disable this new behavior.