Add New Filters on the Supervisor Role on the Employee Tab
From the Supervisor Role on the Employee Tab, allow the Supervisor to choose whether they want to display the list of employees in Seniority order. When a Supervisor decides to display the list in Seniority order, the Employee Profile would also be displayed in Seniority order as well.
Also, include additional information in the Employee list next to each corresponding employee showing why they were ranked in that order (Example: Your company choose to conduct Seniority by company hire date. Show the company hire date next to the employee's name.)