Go to Settings - MIDI Settings - Device Settings
Once you selected your device you click - configure
In that window go to the - Option tab
At the middle of that window you will see A bar - Select the page depending on channel number
You can also change the order of the pages simply by dragging the page up
Look at the link : it is a project I did for a festival - first half of the video Cubase is running the music and MIDI channels
of the piano bass and drums each instrument have its own MIDI channel that goes to a different page in Beyond.
Second half of the video keyboard is used for triggering cues in live through another MIDI device with it own MIDI settings in Beyond.
Both devices can work together.