How can I add a new tracking number to an already existing shipment that was created using the following endpoint link ?
I can create the shipment for a sale/order with the initial tracking number/s, but if I use the same endpoint from above to add a new tracking number for the same order/sale, I get the following error: "you can't create a shipment without products"
Which endpoint should I use? Is it this one or some other? I am a beginner and magento-documentation is confusing for me.