delegate history

I have a request from our operational area to show delegation history on the iexpense auditing page.  They want the actual person who was delegated to and who approved the expense report to show up in the approvals history.  Does anyone know of a way to do this?  Even if I personalize the OAF page, is the delegation history available and from what table.  I know I can add the approval history table function to the approval notification pretty easily, but they want it on the Audit page in case there's an audit.