How to reach new VMs in a VPC/AWS environment

[spiny]

Hi All!

I'm very new to the network/pfsense world. so probably my question will  not be very clever.

However, I created  a VPC in AWS and I have put pfsense as  mainrouter/firewall, therefore if all the the VMs inside the VPC want to go out from the VPC they should pass through pfsense.

My question is: since I can create/shut down as much as VMs I want, How can pfsense knows that there are new VMs  and hence new IP addresses? there is a protocol that allows me automatically to know if there are any changes in my VPC?

Thanks for your help!