Moderator Notice
I am moving this from private messages to a thread so I can add attachments, and so that others can chime in if they see something I missed.
From CC-Peter:
I read your description how to add custom columns to grouping drawer in calibre companion. By the way: great app, that prevents to have two libriaries in parallel, one in calibre and another one in your reader app. It worked as described. Database has been reorganized and the new "Name" appears in grouping drawer. But unfortunately the content of this column from calibre (itīs a yes/no-parameter) does not appear. The custom column is visible in the datails of each book (green arrow for "yes" and no entry for "no") but in the grouping drawer just the name appears, tapping it does not show e.g. Yes<45>, NO<15>.
Or do I understand the intent of adding custom columns completely wrong. What I want is to bring a user defined Yes/No-parameter from calibre to CC to group on it.
CC for itself contains a read-flag, but this will not be transferred back to calibre. So I generated "Read Yes/No" in calibre for grouping.