I am using USPS for USA-based orders and DHL for international orders. I have 6 products in total i.e. 5 of them are t-shirts and one is snapback. I created two packages using USPS packaging i.e. Priority Mail Padded Flat Rate Envelope for T-shirts and Priority Mail Large Flat Rate Box for the snapback. Shipping is working fine for T-shirts but when someone orders T-shirts with a snapback, prices remain the same for shipping for customers.
So my question is that I need to create an accurate profile for items that go in a box: Snapback. If a customer adds a shirt, it can ship a normal profile. If they add a shirt and a snapback, it must ship in a box.