I’m guessing livres is books in english, and it is name of a group.
You are now allowing reading and answering to group livres, nothing else.
You can do something like this (so sorry, it is in finnish):
- first group
gurucan read, answer and start a topic - second group kaikki is
everybodyand that is what you are looking for: no matter what’s the status is everyone can read - third one is everyone who’s logged in: they can read and answer
- fourth one is group of category moderators
Can similar one work to you?