Is there a way to create a Shipment from an existing order using Sage 300 Web API? 

The API allows us to create both an order, or a shipment using the QuantityShipped field on the OrderDetails object.

By using the QuantityShipped value, Sage will create both the Shipment AND the associated order at the time the transaction is created. This isn't exactly what I'm trying to do.

I'm trying to create a new Order (eg a booked order).  Then using the OrderNumber from this original order, create a new Shipment based on this OrderNumber.  This would be used to create our order backlog in Sage, and then create the shipments when the orders are fulfilled.  Has anyone done something like this using the WebAPI?