Edit packing slips

Hi,

I am trying to find a solution for the following:

When customers place an order with several products from several categories, the products appear on the packing slip in the same order as the customer added it to their cart.
When I create the PDF, they also appear in this order on the PDF, but for the people who need to fulfill the order, this is not very handy, especially when there are a lot of products.

Is there a way to have the products appear in the same order as the categories are in the store? If not, is there maybe an easy way to edit the order, before creating the PDF?

If you know a solution, i would be very happy with it.

Regards, Ben