How to realize the return of Tracking Number through the order API?

eg.

we have a order A, it has 5 SKUs, we should split it in 2 package, every package has a tracking_number.

Now, we need send the 2 tracking number to your system without manually in our shopify’s store.

This is the endpoint you should use: https://shopify.dev/api/admin-rest/2021-07/resources/fulfillment#[post]/admin/api/2021-07/fulfillments.json

You will create two separate fulfillments, each assigned to the same order, but having different line items.

We find it can work. Thank you so much.

Pardon me. We need to ask again about this lineitem_ Which field is ID in the order? What Id does it represent? please view the pic under the reply.

This is line item id. You can get them when you query orders or specific order: https://shopify.dev/api/admin-rest/2021-07/resources/order#[get]/admin/api/2021-07/orders/{order_id}.json

It’s under "line_items: { “id”: xxx,