Airport Extreme and Multiple Networks

Situation: So, a somewhat unique situation:

I have two Extremes and currently use the last generation. The other is a 3rd gen, currently disconnected. This mess of equipment is networked among an old desktop, that being a pre-Intel QuickSilver 2002 PPC, two recent iPads and an old HP printer. To get them to all talk seems to require creating a second network: one that works with more recent security protocols ( currently in use ) and the other the riskier WPA/WPA2 Personal protocol. This older protocol was used by the desktop with the 3rd gen. I wanted to upgrade the setup with the 6th gen but it won’t fully work with the desktop. The reason for this is that the 6th gen Extreme will not recognize ANY password I throw at it to connect the desktop probably because the QuickSilver is bound by age. The only way it will work is with NO security, a non-starter of course. This is largely because the QuickSilver maxxed out at Leopard, OSX 10.5.8. The point of the upgrade is to protect the iPads while still being able to wirelessly print from the desktop. We’ve successfully printed via the old Extreme setup, which was the 3rd gen/QuickSilver setup AND iPad using HP’s SmartPrint.

Solution: Create a second network with the 6th gen removed, the 3rd reconnected, create the new network, then swap out routers. But when I looked for the new network, it can’t be found. Apparently the new network is ultimately tethered to the router that created it.

Workaround: Can I tether the 3rd gen with Ethernet to the 6th gen to get both networks on the desktop from which to choose? This way I can wirelessly print from either the iPads or the desktop using SmartPrint.

I know this is a weird situation. “When the going gets weird, the weird turns pro.”

Thanks!