Product Bulk Edit Categories

I recently added a new hidden category page, linked from a banner on the homepage to show all of the products from a particulare manufacturer. Actually made a couple of them. I wanted to add the new “category” to all of the products (dozens for each manufacturer) so I went to products and selected all by that manufacturer and did a bulk edit for category. I added the category and clicked apply. What a panic when it overwrote all of the existing categories. Can we have a drop down selection for the category bulk edit to either “add categories” or “overwrite categories” please. Thanks.