In the nicest possible way ...
Aside from it being a very simple question which has already received a very simple and complete answer - it can't do that, ...
Hello bs27975,
I am not sure whether I understood your network topology correctly...
You don't need to to answer what was a simple question.
You are connecting two different networks at the LAN side of the router? Why?
Because it suits me to do so, and is appropriate.
This would only make sense to me if one of the two nets is connected to the WAN side.
Sorry, I can't speak to what makes sense to you.
Here's an easy explanation - not my setup, but generic to the reason for the question.
Suppose you have a house with a single internet provider.
Now suppose each floor has a different tenant, so you put a router in front of each floor, the WAN link of each goes to the LAN link of the router connected to the provider, who's wan link goes to that provider. Simple, easy, and prudent security measure. No tenant can see inside another tenant's network.
Now behind one of those floors is an IP printer.
So, for simplicity's sake, assume 192.168.0/16 is the house. .0/24 is the first hop inside the house. .1,.2,.3/24 are the 3 floors, connected at .0.1,.2,.3. The printer is at .3.100.
How does someone behind .1.0/24 get to the printer?
route 192.168.3.0/24 192.168.1.3
Problem solved.
Except ... the router won't take a static route.