How to stop self approval in absence management

Hi All,

We have a requirement where all absence request is approved by an HR (based on AoR).

Now if the HR himself is submitting absence request, its coming back to him for approval.

We have fixed this issue by enabling "Prohibit User self-approval" and enabling checkbox "Reassign approvals to those users' managers"

But this solves problem partially only.

Now if the line manager of the HR is submitting leave request for HR (using my team) approval is coming back to line manager, we expect this to go to line manager's manager for approval. Line manager should not approve it as it is submitted by him only.