Our main products ship free. Our Accessories and Spare Parts do not. (Yes, it would be easier for all if everything shipped free but it doesn’t work that way.)
If the customer buys the main product and ADDS an accessory or spare part, we can ship them in the same box and we want that accessory/spare part shipping fee to disappear at checkout.
I have a general shipping rate created for the main products at Free.
I have custom ship rate fees created for the accessories and spare parts.
How can I make this work?