When creating a Shipment (Pick Ticket) chances are that the quantities required to be shipped may be short, BUT the customer process mandates to Pick the Order what is available. Once Picked the Shipment is still waiting to be shipped until ALL the Items are in.
Once the rest of the goods for the Sales Order are received a second Pick Ticket should be created for the same Sales Order for the rest of the items. This is NOT possible today, as it forces either to Confirm the first Shipment (resulting in multiple Shipment Numbers against the same Sales Order) OR the other option is to ADD to the existing Shipment. The second option has an issue with this is version control of the Shipment (Pick Ticket) which is already in the warehouse and has already been picked or is in the process of it being picked.
The "Shipment" as a final step should be able to consolidate all the Pick Tickets(s) on one Sales Order OR even consolidate Pick Ticket(s) from multiple Sales Orders (maybe a Customer has multiple Sales Orders open and ready to go out at the same time).