Amazon Outbound MWS Fulfillment API: Understanding Shipments and Packages

I'm using the MWSOutboundAPI to create fulfillment orders on Amazon.com

In implementing the schema there is a design pattern that has me in a bind.

Amazon represents their FulfillmentShipment as a list on the Fulfillment Order. That makes sense because one order can have multiple shipments if, say, Amazon has to split up an order with multiple items across a few warehouses. This FulfillmentShipment contains the items that it comprises and it contains a list of packages.

Here's where the problems begin because there can be multiple FulfillmentShipmentPackages for one shipment. Each one of these FulfillmentShipmentPackages contains a tracking number, but no information about what items are being shipped in the package.

We would like to be able to communicate to our customers what items have been shipped in what package and this doesn't seem possible given the structure of the API. I was wondering why this is the case and if anyone knows how to determine this information.