We would like to control the epics completion on the mentioned due date. The project manager should mention the project start date at the time of creation of epic, then add the due date once it is planned in sprint, and in case the team isn't able to complete the epic as per the mentioned due date, no one can change the due date once added and an automatic notification should be generated to project manager for adding the new date in the revised end date.
How to achieve this? We have currently three fields for the purpose but not sure how to freeze the due date field once added and generate notification for the new date addition