In the past we have successfully set up erc ha by just entering mgmt ip for both devices on the console and add primary first then join secondary and change the shared ip setting but then now realized in the actual HA config doco that I need to initially configure the mgmt ip with the shared IP address then it will float it around it during the setup?
The correct way is to add one receiver to the devices in the ESM GUI and give it the shared IP. Then go to Reciever Properties > Receiver Configuration >Interface > HA Receiver. Here is where you will setup the management ips for both the primary and secondary receiver. Please make sure the wire configuration is correct before going to setup the IP's and that the ESM can reach all three IP's to start. I hope this answers your questions.