Load balancer and NAT rules wtih exchange.

I have two exchange 2010 servers behind my firewall. i have configured DAG. Now i need to loadbalance OWA. I dont know how to do this with Astaro.

i currently have a FULL NAT rule going to one of the exchange servers and it works without issue. I found no problem configuring server loadbalancing but i dont know how to NAT that. i assumed that creating a loadbalanced group would creat some virtual item that i could put in the NAT rules but it didnt.

my FULL NAT looks like this.

source (any)
protocol (HTTP/HTTPS)
destination ( external IP)

DNAT Destination ( exchange server 1)
DNAT Protocol (none)

SNAT Destination (Internal IP)
SNAT Protocol (none).

any help would be greatful. I searched the forums and the astro website but only found generic answers.

Thank you.

:(