Static Routing on CGM4981COM inside my network

I have another wireless router inside my network which fails over to a 5g backup in case my primary internet goes down.  It's currently wired into my Xfinity gateway and gets a reserved DHCP address.  This is for our WFH connection, other devices are connected to the gateway wifi.  I can't find anywhere to set up a static route back towards my LAN.

For example. I need to route to 10.100.1.0/24 (WiFi subnet on the WFH router) via 192.168.100.254 (WAN address of the WFH router).  Can this be done on the CGM4981COM router? 

Cisco command I'd like to emulate:     ip route 10.100.1.0 255.255.255.0 192.168.100.254 des WFH Subnet

I have two printers on the 192.168.100.0/24 which I need to access from the WFH subnet, which is why I need to be able to reach the WFH subnet from the Xfinity LAN subnet.

Thanks.