Color sub categories same as parent category – only display parent in legend

Is it possible to color sub categories the same as a parent category – but only display the parent category in the legend?

For example, I have four parent categories– 1, 2, 3, & 4 — each has two sub categories — A & B. If they are all displayed, the legend becomes a long list of 12.

I would like the events for sub categories A & B of parent category 1 to all be colored the same. Then, in the legend, display only the parent categories.

(I would just reduce the total categories to the four parent categories, but there are also pages that display events in only one sub-category.)

Any suggestions? Many thanks!

http://wordpress.org/plugins/the-events-calendar-category-colors/