You may notice that when sending a shipment with multiple boxes to DHL.de, you don't receive that number of labels back. Instead, you just receive one label.
This is currently because of a restriction from the DHL.de side of things that prevents multiple boxes being specified to them, meaning that only one label will be returned.
For now, they suggest that if you require multiple labels for an order, you'll need to send through multiple shipments for that order instead, to create multiple bookings with DHL.de for this. Either doing this from your channel to send multiple shipments to Shiptheory for these orders, or manually creating new orders for these in Shiptheory is what would be required there.
Please see some information about creating new orders in Shiptheory here.
If you have any questions or issues, please feel free to Contact Support.