Sale on a product in just 1 of 2 categories?

Hi, is this possible?

I make candles & offer a fragrance-free option. Currently I have the fragrance-free in the fragrance dropdown list with the price reduced when that option is selected. This is a pain for me because I also have sample packs, & have had to create exceptions to each option on each sample product, which is a pain to edit whenever I add a new fragrance to the global fragrance option.

Make sense so far?

So in an attempt to make edits easy, I tried creating a new category for Fragrance-Free, then I added all my products to that category as a secondary category. I then created a catalog promotion & in Conditions, I added the Fragrance-Free category. In Bonus I added the discount.

This reduced the price for the product in all the categories it's in, not just the fragrance-free category. Is it possible to do what I am trying to do? I don't understand why have the option to add categories if it's going to apply it to all categories, or did i just configure it incorrectly?

Thanks in advance!