Dear engineeringideas,
Greetings from team eBay!
Please note that you will not be able to book multiple boxes on eBay Global Shipping (EGS) however you can combine multiple orders. Kindly click on the combine option instead of split. You will be able to combine the orders successfully.
Please refer to the below link for further details-
https://www.ebayglobalshipping.com/how-to/book-shipment-process-flow.
In case you still wish to book multiple box shipment, kindly drop a mail to ops@ebay.com for a manual approval.
We're glad that we were able to address your query today.
Regards,
eBay IN CBT Team