In my forum, the “basic instructions” post is common for 4/8 categories. One option for me is to post 4 seperate posts of the same text (instructions) and pin it to the top of each category. But I was wondering if there any way to do the same with only one post and making that post appear in 4 categories. That would improve the maintainability.
It’s not possible to have a topic in multiple categories but you can link to one from multiple topics of course.
You could use a featured topic list and make it appear on the selected categories.
Walkthrough Add a featured topic list to your Discourse homepage or theme component GitHub - awesomerobot/discourse-featured-topics
If one wanted to get tricky with code I think you can pin globally then hide by category with css, but that isn’t necessarily maintainable. with just 4 out of 8 might as well do manually and copy and paste for 4 categories.