How do I add the Worker's Current Salary Manager and Worker's Proposed Salary Manager?

Summary: On the Manage Employment screen the employee has been assigned both a Line Manager and Salary Manager. So I am expecting to see an Approval Chain Of for both the Worker's Current Line Manager, Worker's Proposed Line Manager and Worker's Current Salary Manager, Worker's Proposed Salary Manager? Yet I only see the Worker's Current Line Manager and Worker's Proposed Line Manager.

How do I add the Worker's Current Salary Manager and Worker's Proposed Salary Manager to the list of values in Approval Chain Of field?

Content (please ensure you mask any confidential information): On the Manage Employment screen the employee has been assigned both a Line Manager and Salary Manager. So I am expecting to see an Approval Chain Of for both the Worker's Current Line Manager, Worker's Proposed Line Manager and Worker's Current Salary Manager, Worker's Proposed Salary Manager? Yet I only see the Worker's Current Line Manager, Worker's Proposed Line Manager.