2 points
Use routers that support site-to-site VPNs, that way any additional households connect to the main household, and everyone’s IP address looks like it’s coming from the same, singular household.
Note that I have no idea how the Steam client is verifying location. If they send out ARP probes and cut access if they can’t detect the other device running Steam on the same layer 2 network this probably won’t work. People use segmented subnets and vlans in their home networks though, so i would assume that it’s just a public IP thing.
