Sorry, but the confusion and time waste of double posting drives me nuts.
I've redrawn a logical map of your network as you've described it.
If this is what your network is, then when I described above is what you need.
Static route on the untangle to each subnet "below" the untangle with the target being the "external" IP of the router above that subnet.
The routers don't need any special configuration.
If you wish to prevent communication between the two, create two packet filter rules, one blocking packets from 192.168.2.0/24 to 192.168.3.0/24 and one blocking packets from 192.168.3.0/24 to 192.168.2.0/24.