FitFabForty asked a question about 'Sub Groups' on this forum: "Is there a specific forum for Week 5 or Week 6"????
healthunlocked.com/couchto5...
I answered the question, but was not able to post a screen-grab in that answer. Here is the screen-grab that I mentioned.
Yes, if a post is made online (not from the phone app), and is allocated to a specific Topic, then you can display all posts just on that Topic. You won't be surprised to learn that topic "Week 1" has the most posts but pleasingly, Week 9 is not far behind.