Thanks, this worked.
But I noticed that many images are already in a different catalog.
I think it is best to delete this catalog.
Deleting a catalog, is it just dragging it into the trash when C1 is closed and that is it?
Or do I have to do anything else in order to not ruin the database system?
Interestingly, there is no information online on how to close or delete a catalog, not in the manual (when you google you only find a manual for Capture one Pro

, nor in any of the Google search "hits".