Scenerio:

• Agent1 is configured to talk to Proxy1 and Proxy2 ips as active servers
• Agent2 is configured to talk to Proxy1 and Proxy2 ips as active servers
• ProxyGroup1 contains Proxy1 and Proxy2
• Agent1 Auto-Registers with Proxy1 first and is assigned to Proxy1
• Agent2 Auto-Registers with Proxy2 first and is assigned to Proxy2

There is no way in the Auto-Registration action where you can set the agent to be monitored by ProxyGroup1.

You have to go into the frontend and manually do this OR use some form of automation.

It would be good to have this option at the time of auto-registration