Absence Management SSHR 12.1.3 How to Change Approval Hierarchy?

We are trying to find a way to allow our employees to Submit an Absence Request via Oracle Employee Self Service's Absence Management or Leave Absence screen, by clicking on the "Create Absence" entry.

This looks promising as it could a potential solution for us, although our Employee Self Service is currently configured to be running on Position Hierarchy, instead of the out-of-box Supervisor Hierarchy (where a supervisor's name needs to be populated).

When creating an Absence Request via the "Create Absence" button, it seems to default to "Supervisor Hierarchy" for approvals, which is what we don't want to use.