Multiwan with different upstream proxy

[TRitche]

Hi All

I'm from Myanmar. Sorry for my English Language.
I want to setup a Load Balancing and Fail Over Gateway with pfSense.
I have 3 WANs from different ISPs.
2 of 3 WANs use upstream proxy server. And the last WAN is no need to use upstream proxy.

Please check below diagram.

172.20.1.1:8080 <–-- ADSL Modem -----|
Upstream Proxy                                   |
                                                        |
172.21.1.1:8080 <----ADSL Modem------|------------------> pfSense Server <-------------------> Clients (50)
Upstream Proxy                                  |
                                                        |
No Proxy            <----Satellite Link -----|
Direct to Internet

How can I setup pfSense with above condition?

Thanks

Thomas Ritche