That's the second option yeah, to make a module to store the split shipment information and store it in the item's custom data, then modify each shipping provider to look for that when processing, but if i can overwrite the BuildDelivery methods then i don't have to modify each shipping provider.
i'm looking forward to UCommerce.
Anyone else, otherwise i'll try contacting support. Got to be a way to overwrite it, sadly i've tried the below with no luck:
[assembly: RegisterCustomClass("CustomDeliveryBuilder", typeof(CustomDeliveryBuilder))]
public class CustomDeliveryBuilder : DefaultDeliveryBuilder
public override Delivery BuildDelivery()
var baseDelivery = base.BuildDelivery();