Although Bluepark allows individual products within an order to be set as shipped, Bluepark does not assign a unique shipment or fulfilment identifier to orders.
It is currently not possible to process multiple shipments for a single order with Shiptheory. Therefore each order must be processed as a single shipment.
It is still possible to define the number of boxes within a shipment, see How to Specify Number of Boxes for a Shipment in Bluepark.