Querying AWS to add hosts with add_host

[M GS]

When using the ec2 module I can register hosts when they are initially created. Is it possible to query aws and register existing hosts?

For example right now I start a few machines and set the exact_count and count_tag. This works well because it allows me to just change the count. What is to still register using add_host, so the rest of my playbook can continue as usual, weather machines were actually added or not.

Thanks!