Once you've created your custom store in ShipStation you can edit service mappings.
In our previous article, we showed you the Status Mapping, where we were using the default Ship Doc statuses. We mentioned making the appropriate changes if you customize your statuses.
Use Service Mapping to automatically set the shipping service and package type in ShipStation based on your customer's choice of shipping option during their checkout. This selection imports into ShipStation as the value for Requested Service.
As the second of the automated processes in ShipStation, Service Mapping will apply after all product automation but before any automation rules.