I am planning to use Raw+Jpeg feature of my camera and the “Show Only Original Images” feature in RawTherapee allows me to group files which is handy. However, when I find images that I don’t like I cannot seem to find a way for me to be able to delete both the jpeg and raw at the same time.
AFAIK RT doesn’t group files. You can of course choose multiple files to be deleted with ctrl/shift, but I think that for this kind of work a picture viewer is much better.
I don’t know which OS you are running. In Linux you can use geeqie picture viewer which groups jpegs and raws and you delete both of them with a single press of a button.
You could open a feature request in GitHub for a “Delete raw + JPEG” function.
I am on Linux (Ubuntu) and before I do anything else I scan my shots with geeqie. If I delete one there both the RAW and the JPG files are deleted.