Thank you for submitting your query.
Currently, it isn't possible to automate the splitting of costs across multiple Purchase Orders.
As you have stated, at the current moment, you will need to manually divide Purchase Order Shipment Costs and then add them to the Cost Lines in the Purchase Orders.
However, I am glad to inform you that there is a feature on the way which will enable you to split costs across Purchase Orders.
As it is currently in the testing phase, unfortunately, I cannot provide an eta, however, we will certainly notify you once it has been implemented.
Alternatively, you can follow our product releases by clicking here.
I hope this information is helpful, should you have any further questions or requests please do not hesitate to contact us at email@example.com.