MySQL InnoDB add new instance to existing cluster Server version: 5.7.23-log MySQL Community Server (GPL)

I'm running an InnoDB cluster and trying to add a new node, the cluster is a couple of years old and binlogs are being cleared after 2 weeks. 

Adding a new node to a new cluster is straight forward enough because the master has all the binlogs but I can't find anywhere pointing me to instructions on how to add a new node to an existing cluster.

It's in production and I don't want to 'test and see' in case I break something so I'm looking for a definitive set of instructions.

Can anyone assist please?
The old way of adding a Slave might be best:


Stop mysqld on an existing Slave (Replica)
Copy the disk (or at least all of MySQL's stuff)
Change the server_id
See if something in the Master contains a list of servers in the topology; if so, augment it
Start mysqld on both replicas.