wifi bridge if thats what its called
 

So i have a separate broadband wifi as backup but i want to connect it to my main network, so im thinking bridge from what im seeing. But, i want to maintain the current network IP and the new one is on a separate
so the wifi will be on 192.168.1.2 and the ethernet something like 192.168.0.254 static
what i want to do is set it so that any traffic on the 0.254 is sent to the 1.2 and its gateway.
From what ive read a standard bridge just uses the same IP range and bridges across or am i reading it wrong?

There's different levels of doing what I think you want. Essentially, at it's simplest, you want to tell whatever makes routing decisions there that the wifi is an alternative route. Then when it can't access the default route, if you're correctly set up, you have a fall back. The way you do this at home differs greatly to the way you do this in a commercial outfit or isp. There's failover mechanisms used professionally.

Network bridging is this sort of thing: You have a 10G capable feed, but 1GB network cards. If you put 5 x 1G cards in a box, and 'bridge' them you will get a network 'device' close to 5G. That's a relic from the days of slow stuff. It is used today, but mainly in professional outfits. The guy bridging dialup modems is long gone.

what exactly is this "separate broadband wifi"?