Change IP addresses on ISPConfig3 Multi Server Setup?

I currently have 5 ISPConfig3 servers setup under the multi server configuration. I have to change the IP addresses of all 5 servers. How do I do this so that ISPConfig3 knows where to find the new servers and syncronize correctly.

I am using Ubuntu 16.04 and changing the IP addresses in the OS is not an issue. Update the /etc/network/interfaces, /etc/hosts and reboot. But that will break synchronization for ISPConfig3 I believe due to the multi server setup.

 

So the machines are the same. The only change is the IP for each server including master?
I'm no expert but I would:

1. Change the IP addresses first from the GUI of ISPConfig.
2. Change the DNS zone accordingly.
3. GRANT access to new IPs and "ungrant" the old ones.
4. Update the /etc/network/interfaces and /etc/hosts.

First the slaves and the master at the end.

But I'm no expert...