AWS EB Auto Scale Group

When I set up my EB environment, it created a custom AMI, a load balancer, and an auto scaling group for that load balancer.

I needed to add another domain to be serviced by this EB environment, so I added another load balancer in the EC2 console, added the SSL cert for that domain, and put one of the EC2 instances behind that load balancer.

Now I need to make sure the Auto Scaling group that EB created for me has both load balancers in it, however I found out that you can't add or remove load balancers for Auto Scaling groups. So I tried creating a new Auto Scaling group with everything exactly the same as the one that EB created, except with 2 load balancers, but whenever it tries to launch the custom AMI that EB created in this new Auto Scaling group, it fails with the message:

"The parameter groupName cannot be used with the parameter subnet. Launching EC2 instance failed."

So then I thought about modifying the custom AMI that EB created to get rid of the groupName parameter, but apparently you can't modify an AMI that EB created? What am I left to do here?