Hacking discourse to create sub-sub categories

Sure!

Right now, here’s the root of our forum that lists out categories

We click on “Exploring Computer Science” to get the Exploring Computer Science - Code.org Professional Learning Community which renders subcategories for each unit

When I click into the subcategory for unit 1 I get this list of topics

However, what I want when I click into the subcategory is something like

Clicking lesson 1 would take the user to a url like forum.code.org/c/ecs/unit1/t/lesson1 - Essentially all topics in the unit1 subcategory that have been tagged with lesson 1