Whenever possible it is best to make any additions, combinations, splits etc. prior to importing the orders into GroovePacker.
This is why orders are most often imported into GroovePacker manually, by clicking the Import Orders button. It allows changes to be made before running the import.
Sometimes changes must be made to an order after it has been imported into GroovePacker.
There are ultimately 3 ways to go about this.
1- Remove the original order(s) from GroovePacker and then run the import again to bring in the updated version.
2- Make the change, adding an item for example, in both the order source and in GroovePacker.
3- Import orders again after making the change in the order source (ShipStation, ShippingEasy, Shippo, etc) - after the import completes verify the change is reflected in GroovePacker.
ShipStation users can at the "GP Ready" tag to an order that has been modified and it will be re-imported during the next import, updating the changes in GroovePacker.
ShippingEasy users can add a Category label to an order (any label can be used) to update the "Last Modified Time" of the order, which will cause it to be re-imported on the next import.
It is recommended to verify that the change was reflected in GroovePacker during the re-import.
You can find more information on combining orders here.