Squid usually uses the LAN subnets of your network.
To add addition lans, add additional CIDR subnets, to Allowed Subnets on the ACL tab.
For example to add the networks of 10.1.1.0, 10.1.4.0, 10.1.5.0, 10.1.6.0, 10.1.7.0:
10.1.1.0/24 10.1.4.0/22
Remember to restart Squid for this to take effect.