Our UBNT devices have a backup IP capability. I don't want to use the primary pool for this. They all plug into the same switch (SWOS) and into a port with a bridge.
I also have two static IP ranges I need to add as well.
Each time I try I can't add additional ranges to the same bridge. Am I doing something wrong or is this just not possible? If possible, how exactly do I do it?

You can add a second IP address in your Bridge for the cases you want to access the Ubnt device through its fallback IP...
For example, you can add the address 192.168.1.1/24 in the Bridge, then click add again and add the address 192.168.2.1/24 in the Bridge as well...