Internet Expenses

I am at a client site where they have preparers who create expense report for the person (initiator) who incurred the expense.  The initiator certified the report and then goes for approval.  The client would like to approver to have the capability to fix any errors like wrong allocation on the report and then approve, instead of rejecting it or asking for additional information.

Has one done this change (allow approver to edit the expense report) and how do you do that?