Parent Category links question

[Guest]

I was just wondering if there is a way for the parent categories link to automatically display all products in the sub categories of the product category.

For instance:

If I have this setup

Car as the parent category
Nissan, Honda, Toyota as subcategories

When the user clicks on car, is there any way it will display every product in all three subcategories?

I ask this because I imported over 2000 products on my site, and really do not want have to manually change each product to go into the parent category as well. If there isn't a way to do that, is there a faster way to update my products. I have Presta QuickUpdate, but it does not really help in this regard. Any help is much appreciated!