How to setup expense report approval rules for managers

Summary: How can I setup expense report approval rules for managers (people who report directly to the CEO) and for the CEO who delegates his expense reports entries to his personal assistant?

Content (required): We have three different scenarios for the expense report approval

1. CEO expenses made by his PA - this scenario causes the following error message when the expense report is submitted: "The following error occurred during expense report approval. The supervisor or job level associated with the approval rule doesn't exist. Change the rule or correct the HCM employee supervisory or job level hierarchy."

These expenses should be automatically approved and should not require the auditor's approval (Audit rules are already created and working)