The owner of the cart I'm working has unique part numbers for each product that represents not the main product, but each unique combination of product and it's attributes.

For example, a tee shirt.
PN# 1001, Tee Shirt, Red, Small
PN# 1002, Tee Shirt, Red, Large
PN# 1003, Tee Shirt, Blue, Small
PN# 1004, Tee Shirt, Blue, Large
Other than entering as 4 distinct products, is there any way to do this?
Better yet, is there any way to do it and maintain quantities for each item combo?

PN# 1001, Tee Shirt, Red, Small, qty = 4
PN# 1002, Tee Shirt, Red, Large, qty = 22
PN# 1003, Tee Shirt, Blue, Small, qty = 8
PN# 1004, Tee Shirt, Blue, Large, qty = 55
Thanks!