Approval flow contingent on #of days requested

Our CEO is set up as a "Tier 2 approver" for leave for all of our employees. However, he only wants to approve leave requests that are >3 days. Any leave requests for less than 3 days will only need the employee's direct Manager to approve and not need secondary approval.

Our stop-gap measure:

All of our Teams have the HR Manager and an Admin listed as Primary Secondary Approvers and the CEO is listed as an Alternate.

HR Manager will provide secondary approval for all requests less than 3 days - concurring with the decision of the employee's direct Manager. If a request is more than 3 days, she will forward the email to the CEO for his approval. This way the CEO will only get notification for employee leave requests for 4 days or more.