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[JammyDodger]

These maybe of some use:

Private Topics Plugin

Summary Private Topics Enables private topics in a regular category Repository Link GitHub - communiteq/discourse-private-topics Install Guide How to install plugins in Discourse Features This plugin allows you to add an extra security setting to categories so that users can only access their own topics. You can also designate one or more groups that can see all topics in the category. This is typically used for providin…

Discourse Restricted Replies

Summary Discourse Restricted Replies adds a per-category setting allowing staff to restrict replies on topics to the topic creator and members of specific groups. Repository Link https://github.com/discourse/discourse-restricted-replies Install Guide How to install plugins in Discourse Features This plugin adds a per-category setting allowing staff to restrict replies to the OP, and members of specific groups. This is a bolt-on t…

(The latter less so if visibility is the main criteria)