Just be on the same subnet - then you use the normal 'search for device' and the brain will find devices on the other brain as well. Example: if brain 2 has an "Apple TV" device - simply search for "Apple TV" on brain 1 and the device will appear.
Marco Nighttronica Preißig just setup the devices(add device) to the second brain and place that brain where your going to use it. Leave the cabling wizzard and don’t add favorites as you’re not going to use that brain further.
If all your devices are added to your second brain then connect the app to your first brain. Add a room on the first brain with a name that resembles the location of the second brain. now add a new device to that room and search for NEEO brain. It will show you all devices that are installed on the second brain, you can add them one by one and follow the cable wizzard and add favorites. Connect all remotes to the first brain.
as a reference I have all remotes paired to our livingroom brain. All other brains and their devices are controlled through our livingroom brain. The remote are all the same and every room has one.