Can you add multiple box-dimensions?
Optimize shipping labels with multiple box dimensions. Our page guides you to create box groups and set up shipping rules based on box dimensions.
No.
You can add one box dimension and empty box weight in our dashboard.
Note that a lot of carriers do not base pricing of return-labels on the exact box dimensions but rely heavily on weight of the return. Therefore check with your carrier in detail. Even though you might only be able to set a single package dimension in our dashboard it might not make a difference with the carrier.
See here how we calculate the total weight of a return: How is the total weight of a return calculated?