Multi-WAN external IP issues

[vitafit]

Hi together,

just a simple question: I habe some kind of Multi-WAN NAT scenario running - my pfsense-installation has 6 ipv4-public addresses. Between them and a bunch of virtual-maschines behind the pfsense i use NAT. So like this:

Public IPV4-Adress ->  pfSense [NAT]  -> Maschine1 (first IP), Maschine2 (second IP) …

So far it works fine for me except one problem: My outgoing IP is always the public pfsense-ip. So Maschine1 and Maschine2 have the seem outgoing IP if you check on http://www.whatsmyip.org.

Is there a way to match and "spoof" the outgoing ip?

Thanks!
Kind regards
Vitafit