Assigning product to category via .csv file removes original category assignments

[mborden]

I have a new category that I would like to assign specific products to and these products are already in existing categories. I'd like to keep them in their existing categories as well. When I imported a test file to see what would happen, the products get assigned to the new category and do not retain the categories prior to the import. 

Is there a way to keep the original categories without having to find each category ID to re-assign them to?

[Tom Robertshaw]

Have you tried importing via path instead of category IDs? Which import process are you using?