How can I get all the delivered change sets in event handler?

Hi,
I have the following needed: i need to change the state of a work item after all the linked change-sets have been delivered. In order to achieve this I initially develop 2 extension:
- a followup of the delivery operation that gets all the change-set links and verifies that are all already delivered an then perform a change of state
- a precondition on the save work item that blocks the change of state if not all the change-sets have been delivered

The two extension work well one by one but when runned togheter (like in the last deliver) I have a big problem: in the save work item precondition (triggered by the followup change of state) I cannot see the change sets in delivery as part of the history of the target stream (probably because the entire operation is still running).

So I change my first extension in an event handler, of category com.ibm.team.scm.eventCategory.delivery . The problem is that the event handler is called only one time for every deliver, regardless how many change sets are involved (correctly), but the event.getItem() returns only ONE change set (the older one) and not all the change sets involved (they are mentioned only in the event description but I don't like to rely in regular expression on a pre-compiled string).

What can I do to get all the change sets involved?

Thanks,
Michele.