LAN Segmentation

There are 5 PCs at home that I am trying to connect to our LAN. Two were recently added requiring an additional router. I have uplinked the second router and thee WAN works fine, but of course, my network is now segmented. LAN 1 uses 192.168.1.0 and LAN 2, 192.168.2.0, and the range of addresses have been added to the firewall settings on the respective PCs.

Without having to install NICs on all the units, how can I get the PCs to see each other across both networks?

Needless to say, this is important for printer sharing and so on.

Thanks in advance for your help.