Have not tried this for a while, so I'm not sure if the steps are the same.
To ship multiple boxes for your order, click on the link that says 'Ship Multiple boxes for this order' at the bottom of your 'Label Completed' page.
Another method is to create subsequent labels by clicking on the 'Details' link next to the payment from your buyer and click 'Ship Another' at the bottom of the Details page.
To create multiple labels for single payment:
Login int to your account.
Go to your Transactions.
Find the PayPal payment from your buyer for which you created the first label.
Click the "Details" link in the Details column of the payment.
Scroll to the bottom of the Transaction Details page.
Click on "Ship Another."
Create another label as needed.
Note: Make sure you select the Details link next to the payment from your buyer and not the Details for your shipping fee from USPS or UPS.
