Importing to multiple PARENT categories

I have products that need to be imported into various PARENT categories. Example:

Parent categories are:

Riding Apparel
Children's Riding Apparel
Boots and Half Chaps

Children's Riding Boots would need to be shown in all 3 Parent categories. So far the import only allows a single parent category listed in the product_parent_id heading.

How can I make this happen> It's extremely cumbersome to change the parent category 3 times, or go into EACH product and assign a new category.


Note: the arrangement of categories is consistent with other sites in the customer's industry.

Sorry, meant parent_category

If it were as simple as you'd described

My csv is set up as follows:

product_code
images
product_tax_id
product_parent_id
parent_category
categories
product_name
product_description
price_value

Note that there is a PARENT category and CATEGORIES. I need to be able to do ONE import of a list of products and assign them to multiple PARENT CATEGORIES. To better illustrate, Category tree looks something like the following:

Riding Apparel
-Tall Riding Boots
-Paddock Boots
-Half Chaps
-Coats
-Shirts
-Breeches
-Belts

Boots and Half Chaps
-Paddock Boots
-Half Chaps
-Riding Boots
-Tall Riding Boots

Children's Riding Apparel
-Tall Riding Boots
-Paddock Boots
-Half Chaps
-Coats
-Shirts
-Breeches
-Belts

worked PERFECTLY. Thank you!