Create custom taxonomy for multiple categories

Hey Everyone!

I have a lot of categories – 140 – but for building a custom search I really only need the parent/child categories – I don’t need the grandchildren.

I’m going to create a custom search and I don’t want all those categories to be available as filters, I only want 4 top level taxonomies, each containing 4 more, and have the ability to “map” multiple categories into each custom taxonomy.

There seem to be many custom taxonomy management tools, custom posts to taxonomy tools but I’m having a hard time finding a tool to creat taxonomies in the way that I’m looking for.

Does anybody know of such a plugin that I could use?

Thanks for your help!
Rob