Squid src rule to keep clients ip

Hi

Ive got an setup where my clients got 3 different ip ranges (10.5.60.0/24 ; 10.5.65.0/24; 10.5.70.0/24

My firewall with 3 WAN lines ip - 192.168.4.34/29; 192.168.4.50/29

and my squid box - 192.168.10.254

My Squid has got an WAN and LAN (WAN - 192.168.4.54/29, with gateway 192.168.4.50) LAN (192.168.10.254/24)

Now my clients get split on the 3 Wan links where each subnet gets its own WAN link, with mangle and route marks
I have enabled the web proxy, with parent proxy > squid. and It works
Problem is, now all the my clients subnets, goes out on 1 WAN interface, leaving little traffic on the rest.

I mangled my clients ip and redirected it to 8080, for the squid to work, How can I keep my SRC ip’s?