How Can I Prevent Comments and Attachments to Completed task in FCCS Task Manager

Summary:

How Can I Prevent Comments and Attachments from being added to Completed task in FCCS Close Task Manager before we lock the period?

Content (please ensure you mask any confidential information):

Reviewers and auditors cannot tell if users have updated tasks after the approval and/or audit was completed.

We have a report that can indicate if some one has added an attachment after the task was approved and closed but our Internal Audit team does not want to worry about people doing this or being called out for it by external auditors.

Obviously we can stop the edits after we close the period but we are exposed to this risk until we are ready to do that.