Two Lan Network for Two different WAN

Hello Guys, 

I've tried to search, but without any luck. Basically I have a very simple configuration:

LAN1 192.168.X.X  --> WAN 1

Now I would like to modify the configuration, in this way:

LAN1 192.168.X.X/24  --> WAN 1

LAN2 192.168.Y.Y/24  --> WAN 2

Where WAN 1 and WAN 2 are two different providers, with two different addresses and network
My questions:
1) How to configure Sophos XGS (SFOS 20) to do that?

2) How to be sure that these two networks remains separated at all, also if they uses same Sophos?
Thanks,
Alex