The process to create a multi-package shipment in V3 is a bit different than in V2.
If an order needs to be contained in a single shipment but is too large to fit in a single package, use the multi-package shipment option. ShipStation will print multiple labels for a single shipment, with each package customized in weight and dimensions as needed and tracking for each.
NOTE: Not all carriers support multi-package shipments (for example, USPS does not allow this option, but UPS and FedEx do). If the carrier you're using does not list this package option, you can use the Create Another Shipment action after you create the first shipment to create additional shipping labels.
Create a Multi-package Shipment
Click the Shipping Service drop-down menu and select a qualified service.
Click the Package drop-down menu in the Configure Shipment Widget.
Choose Multi Package under the Carrier you wish to use.
NOTE: If Multi Package is not available within the carrier package options, the carrier does not support multi-package shipments.
ShipStation will open the Multi Package Shipment editor.
Add as many packages as you need (click the down arrow to add multiples of 5, 10, or 15 packages at once).
Set their weight, size, and insurance options.
If this is a package configuration you'll use frequently, check the box to Save New Package Set and name it.
Click Save Packages.
The Configure Shipment Widget will show the number of packages for this shipment next to the package drop-down menu.
To modify the packages on this shipment, click the # Packages link to reopen the Multi Package Shipment editor.
When you click Create Label, the corresponding number of labels will be generated and available to print.
NOTE: While each package will have its own tracking number, only the master tracking number will appear in the Shipping tab's Tracking # field.