How can I set up code for initiator in approval hierarchy?

Summary:

Scenario: There are 3 approvers and the employee is the initiator of the absences. If an employee is initiating, hierarchy is working fine. But the requirement here is: if the initiator is 2nd approver then according to the hierarchy it sends approval to 1st approver.

Because 1st approver is the employee's line manager and 2nd approver is the Territory Manager and 3rd approver is Back Office Users.

It should work like this:

Employee> Line manager> Territory Manager> Back Office.

If Initiator is TM> Back Office. (it should not send approval to the Line manager).

I need to write the code and apply conditions to the initiators.