Good afternoon,
The scenario of adding a new member to the cluster when RDS is used is straight forward and stand practice for expanding the cluster. The area I have of concern is converting a development cluster to production. We have seen the setup in development normally don't conform to best practices with policy and audit configuration which can cause performance impact. Also what is the plan for future development and testing scenarios. I would recommend standing up 2 new nodes to form a production cluster then using GMU to promote service/policies between development and production.
Sincerely,
Stephen Hughes
Broadcom Support