Plugin to Manage External Links with Hierarchies

I’m looking for something to help me create a page (or pages) of my external links. I would love to be able to create parent categories for these and create a hierarchy of subjects.

For example, have a parent category of Homeschool and under that have Art, Math and Science categories. (Currently, the link categories are the only categories that don’t allow parents. Page and post categories do.)

My ultimate goal is to create a Resource page for my readers. Any thoughts on the best way to do this?