How to exclude top layer terms in filter?

Hey everyone!

Quick question about taxonomy filters - I’ve got a two-level term structure and I’m trying to set up two separate filters:

  1. First one to show just the parent terms
  2. Second one to show only the child terms

I can see how to show top-level terms, but what’s the best way to display only the second-level ones? Anyone done this before?

Thanks!