massaction on predefined fields

-- url of the page with the problem -- : www.aroma-massage.it

I created some default fields in the product management page to assign extra categories to the products to work with the filter.

since I forgot to insert these default fields for some product categories, I wanted to understand if it is possible to perform a massaction to assign some of these default fields to the products.

I was trying to set the massaction as follows but I got stuck and I don't want to mess it up.


any suggestions please?