PO Release Workflow

Hello All,

I have just started working on workflow and while creating a workflow for PO release with 3level approach, i have encountered with small problem.

When a PO is created, the first level approver is identified and workitem is sent to his SAP Inbox. The work item description shows the PO value (suppose 2000USD). Even before this is approved by the approver, there is a change in PO and PO value is reduced to 1800USD workflow gets triggered again and a new work item appears in first level approver's inbox with New PO value (USD1800).

However, the old work item still remains in his Inbox leading to confusion. Can anybody tell me how can i ensure that as soon as a new work item is generated the old one gets deleted automatically?

Secondly, supposing that even the first level approver has approved the PO so ithe work item is lying at 2nd level approver's inbox. Now some changes have taken place in PO then new workitem gets triggered and old item lying at 2nd level approver's inbox should get deleted (as the PO is going through approval process once again).

Hope i am clear in explaing my problem. Any help in this is appreciated.

Thanks in advance.

Lakshmi Narayana.S