Hi Nimaee,
As you are creating inbound deliveries by using SPADE output from OD, it is not possible to create single inbound deliveries from multiple outbound deliveries. You can create one shipment (TCode VT01N) for multiple outbound deliveries and your forwarder should be charging based on shipment, not based on outbound or inbound deliveries. At my client location, we are creating single shipment for multiple outbound deliveries for forwarder.