Can we add in two calibration points into the performance process?

Summary:

We have a business requirement to add in a formal rating moderation process for performance reviews. Please can you advise on the best way to achieve?

Content (please ensure you mask any confidential information):

Our current performance process is:

1. Employee enters comments and rating into performance doc & submits
2. Employee and manager meet
3. Manager enters comments and final rating and shares & releases the doc

We have a business requirements to add in a 2 stage moderation (calibration process)

1. All managers enters performance ratings for all direct reports
2. Moderation meeting takes place to review ratings
3. Employee enters comments & ratings into performance doc