Overview
To simplify work with orders, there exist several endpoints which allow to add/update/delete single orderItem instead of updating the whole order.
POST {{ marketUrl }}/orders/{orderNumber}/items
PUT {{ marketUrl }}/orders/{orderNumber}/items/{orderItemNumber}
DELETE {{ marketUrl }}/orders/{orderNumber}/items/{orderItemNumber}
OrderItem model defintion: see here
Here is the list of operations you can do with order items: