Can I have mutually exclusive groups?

[ThiloteE]

Heureka , I found a solution for JabRef 5.6 January 2022:

It makes use of including additional conditions into the regular expression, to be exact other labels or keywords. The example uses readstatus=read and readstatus=skimmed to achieve this, but in theory other fields are possible too.

• Configuration for the three groups included, excluded and to do:
  
  
  

• Known problems:
  Using this specific solution, entries cannot be manually moved from included to excluded group anymore using the add selected entries to this group button.
  

Thanks again to @aexel and his post that describes how to create a group based on readstatus.