Display only Subchildren of a Category in the Category Widge

I have a category called "Events" with several subcategories below it. In my categories widget, I can only find the taxonomy id for All Categories, (see attached screenshot) which returns all of my blog and event categories. Is there a way to find the taxonomy id for just Events so I can display only its child categories using the category widget?

I was thinking about this completely the wrong way. I actually needed to set the ContentType of the widget as is nicely documented here www.sitefinity.com/.../configuring-the-categories-widget

Should any other lost soul come across this looking for the same thing, there you are.