Hello,

I believe that the best way of adding new servers to the existing cluster would be to follow steps 2 and 3 each time you need to add more servers.

Alternatively, in case that you are looking for a production-ready solution, what I could suggest is checking out the new DigitalOcean managed MySQL clusters:

https://www.digitalocean.com/products/managed-databases/

This would let you add new replicas to your cluster just with a click of a button.

Best,
Bobby