We are a Canadian ShipStation account user and often ship Multi Parcel shipments with Canpar and Canada Post and Shipstation does not offer the Multi Parcel function, as it does when we ship via UPS and other carriers. This feature would be very helpful and time saving since we currently have to process a multi parcel order one piece at a time and after the first piece is shipped we have to go back into the "shipped" order and process the other pieces, one at a time. It would be much quicker to have the + multi parcel function available.
From ShipStation Support:
Canadian ShipStation accounts only support the multi-package shipment function for the following carriers: FedEx, UPS, DHL Express, and Purolator (Express packages only). This functionality is purely dependent on what each carrier allows us to offer to our users, and at this time Canada Post and Canpar have not signed off on having this added to their integrations with our program.
I completely understand why this would be useful for our shippers, so I do encourage you to post on our feedback forum with this idea.