An organization is planning to create a secure scalable application with AWS VPC and ELB. The organization has two instances already running and each instance h...

An organization is planning to create a secure scalable application with AWS VPC and ELB. The organization has two instances already running and each instance has an ENI attached to it in addition to a primary network interface. The primary network interface and additional ENI both have an elastic IP attached to it.
If those instances are registered with ELB and the organization wants ELB to send data to a particular EIP of the instance, how can they achieve this?