One option is to use the Multi-Order Shipping feature.
* Business Account - How to access Multi-Order Shipping
Login to your account.
Click on "Tools"
Click on "All Tools"
Select "Multi-Order Shipping".
Click "Start Shipping".
Select "Create new order".
* Personal Account - How to access Multi-Order Shipping
If you have a Personal Account, you won't have the Tools feature however, there's a "possible" work around.
Login into your Personal Account.
Next, in your browser's address bar, paste in this link:
https://ship.paypal.com/powership/powership.html
Then press "enter"
When the screen reloads you may see that the app has timed out, click on "Login".
After the app reloads, click on "Create shipment".
Not sure if this will work for you but, at least worth a try.
