Free shipping for customer but enter shipping cost we have to pay for

[FrazeColder]

Hey there,

I am quite new to Shopify and I am facing a problem. My shop offers free shipping above 40 $ spend. However, of course, the shipping is not free. We, the shop owners, have to pay for that shipping in this case.

In order to have correct reports, I would like to enter the shipping costs we have to pay (not the customer).

I know you can enter the unit costs per product. But those unit costs should not and cannot contain the shipping cost. Two reasons for that:  First, shipping costs vary depending on the amount of items and box needed to fulfill the shipping and second because sometimes the customer pays the shipping cost (below 40 $ spend) and sometimes we do.

So, is there any possibility to add such shipping costs to Shopify to have correct reports?

Furthermore, if there is a possibility, how can I add them by using the Shopify REST API?

Does this help me? https://shopify.dev/changelog/add-and-remove-shipping-lines-with-new-mutations-on-the-order-editing-...

Kind regards