Thank you for the information. The mental model that I have right now is, I should add a custom field to tags (like tag_description) called attached_users. For the above example, tag#1 should have attached_users: [“userOP”, “user1”].
Then, I should somehow add this to the serializer and figure how to display it in the post.
While thinking about this, I had another idea. If I use discourse assign (Discourse Assign) to assign these users to topics based on tags. I can already retrieve this information from the topic and I guess displaying it would be easier. However, discourse assign doesn’t provide any way of programmatically adding users.