Requirement to lock all goals in a goal plan after 3 months into the annual review period

Summary:

We are having the following scenario:

Rolling out a Goal Plan for the annual review period. Manager & Employees are adding goals, removing goals etc. The requirement is now that the all actions like adding goals or editing them should be locked down. They can update the goals but not edit or adding.

In my opinion this is not possible - I have found a few people asking similar questions but over a year ago.

Has anyone had a requirement like that and how did you work around it?

Thank you!

Version (include the version you are using, if applicable):