Thanks for your follow up Heliosurge but I want to hide the other posts and only keep one visible.
The purpose is: “that’s the trust 3 forum, if you want to join, you need to contribute and keep civilized”. I think that keeping it visible could be motivational, including post count but not the content of the category.
I’ll try to work that with Discourse API but at the moment I need to finish and publish the site. Maybe we can work on that together (with any interested), my programing skills are very limited but I can do my best and help with ideas, testing or something else.