How can I have multiple/additional subnets on WAN interface in passthrough setup?

The scenario of having multiple subnets on WAN interface, which is configured as pass-through, would be as shown in the following picture:

This can be setup by configuring manual routes as shown in the following steps:

Step – 1 Simple manual route in the “ADVANCED” tab as shown below:

Step – 2 Advanced manual route in the “ADVANCED” tab:

Step – 3 Applying no-NAT for packets returning from WAN1, under the FIREWALL tab: