How to address the issue of changing requirements during Testing Phase?

I have noticed that a lot of times there are changes to the FRD/BRD even after planning phase. This really is not a very good approach if the FRD is updated and sent to the QA team. There would be a lot of rework in the Test Scenarios and Test Cases and a lot of time is involved in this process. This may seem fine as long these changes are taking place in the Planning phase but imagine if the requirements keep on changing.

During the execution phase then there are many chances that the requirements may not be fully tested and a lot of UAT defects may arise. To avoid all these there are some measures given below which have been successfully implemented and saw the result which resulted in the UAT defects being decreased.

1. The QA team needs to make sure that the FRD received is the final approved version from the Business/Development team.
2. Any cosmetic changes can be accommodated during the planning phase.
3. Any functional changes should come as Change Request and should be taken care by during planning phase.
4. It should be communicated to the business or Development team that the FRDs should not be just updated for functional changes if this is the process then it should be intimated to the QA team
5. During execution phase any type of changes should come as Change Request. These changes can be by business to enhance any requirements or because of the defects raised by the QA team some functionality needs to be changed. This should not be changed in the FRD and the defect should not be cancelled.
6. Instead all the changes should come as Change Request and QA should estimate the  effort for planning and execution and should be taken care after the execution phase. The process may defer from company to company.

Conclusion: Any type of changes in the requirements should not hamper the work of the QA but should come in the forms of CRs so that QA team can analyze and have additional time to test.