Can parent category archive page display child categories?

There are 5 parent categories, and each has one or more child categories. I’d like to have a link to a page that lists all posts from the parent and from the children. On the linked page you’ll see the 5 color-coded parent categories. DCF is a good example. The DCF parent archive page does not list any events, but there are 34 events in a child category. Any guidance would be appreciated.

The page I need help with: [log in to see the link]