I use XnViewMP quite intensively for cataloging my photos (tags and description). The rule here is that I keep several files of one photo: RAW + JPG and possibly TIF. All with the same file name, but with corresponding extensions (eg. IMG_1234.RW2 and IMG_1234.JPG)
In Darktable, these files are automatically recognized by the program as a group and framed in color in the browser (Lighttable) and explained by an info text (see screenshot). This makes the overview much easier.
It is also possible to create your own groups and delete them.
In my opinion, this is a very nice feature.
Could this also be realized in XnViewMP?