Goal Approval need to be configured basis second level manager

Summary:

We need to configure goal approval based on the second level manager.

Content (please ensure you mask any confidential information):

1. If second level manager of employee is Director General (1 person for whole organization), then approval should go only till 1st level manager (line manager).
2. We identified 52 employees whose second level manager is DG : Is there any way to define this rule apart from using person number or assignment number, as in future people might change in the organization -> Job Code & Positions are not unique values hence those cannot be used as a parameter while defining the rule.

It would be really helpful if any ideas or thoughts on this can be shared.