Modify the Auto Scaling group to exclusively use the AZ2 subnet. Recreate the AZ1 subnet with half its original address space and update the Auto Scaling group to include the new AZ1 subnet. Once instances are stable, reconfigure the Auto Scaling group to use only the AZ1 subnet. Replace the current AZ2 subnet with a new one using the remaining half of the original AZ1 subnet's address space. Establish a new AZ3 subnet with half of the original AZ2 subnet's address space and adjust the Auto Scaling group to target all three subnets.

Shut down EC2 instances in the AZ1 subnet, recreate the AZ1 subnet with half its address space, and update the Auto Scaling group to utilize this new subnet. Repeat the process for the second AZ. Define a new subnet in AZ3 and reconfigure the Auto Scaling group to target all three subnets.

Create a new VPC with identical IPv4 address space and define three subnets, one for each AZ. Update the existing Auto Scaling group to target the new subnets in the new VPC.

Configure the Auto Scaling group to use only the AZ2 subnet. Adjust the AZ1 subnet to half its original address space and update the Auto Scaling group to include the AZ1 subnet again. After instances stabilize, set the Auto Scaling group to use only the AZ1 subnet. Modify the current AZ2 subnet to use the remaining half of the original AZ1 subnet's address space. Create a new AZ3 subnet with half of the original AZ2 subnet's address space and update the Auto Scaling group to target all three subnets.