Feasibility of Syncing Manager Rating and Manager Calculated Rating

There is a requirement in Performance Management where the Manager Rating and Manager Calculated Rating need to be in sync (i.e., the Manager Calculated Rating should be equal to the Manager Rating by default).
Currently, we have enabled the manual rating option in the Performance Template. This is required so that when performance data flows to Compensation, the ratings remain editable, as per Oracle documentation and community recommendations.
However, the business requirement is as follows:

The manual rating should remain enabled (to support Compensation integration).
At the same time, managers should not be able to edit or modify the rating in Performance Management.