Thanks a million, I will try this after I get back from work !!

If you use topic Room:SubTopic_ID for a subtopic, that’s just a new channel for just that one chatroom.

I usually use this to ensure that a message only gets sent to the appropriate channel topic.
broadcast!(socket, "topic:#{subtopic_id}:new_message", msg)

If you want to load older messages, you’ll need to do a bit of legwork. This would mean writing a query for loading older messages and running it in the :after_join channel event.

Also you’ll need to add them to the chat in the front end.