First I have these categories.
Categories:
Paint Brand 1
Paint Brand 2
Paint Brand 3
Then these tags
Tags:
Red
Blue
Green
I want two combo boxes. One where you select the Paint Brand and one where you select the Colour.
So if you selected just Paint Brand 1 you'd get all the colours within Paint Brand 1. But if I selected Paint Brand 1 and Red, you'd get only the red from Paint Brand 1
