To add an approver to a report:

1. On the expense report page, select Details → Approval Flow
2. Click the Add a step before this step button to assign a new approver to the workflow prior to the desired step - OR - 
3. Click the Add a step after this step button to assign a new approver to the workflow after the desired step.
4. Click the Remove this step button to remove a workflow step that has been added.
5. Click Save Workflow.

Note: when a report is returned for correction, the additional approvers are removed from the default routing. i.e. you'll need to repeat the process of adding approvers (if necessary).

Ad-Hoc Routing Instructions (PDF)