you can currently set multiple tracks to receive input from a MIDI device, however you cannot currently define parts of the keyboard to go to a track and other parts to another.
I’ve added this to our todo list but I don’t know when we’ll be able to add this feature to n-Track.
If your keyboard/keytar allows you to split the keyboard to send a range of notes to different MIDI channels, then you can set n-Track to record/play MIDI tracks from different MIDI channels. For example set the lower part of the keyboard to send to MIDI channel 1 and the higher part to send to channel 2. Then add two tracks with two different instruments, say piano and violin, set the piano track to record from MIDI channel 1 and the violin track to record from channel 2. You can set which MIDI channel to record from in the popup menu that appears tapping on the track’s circular rec-arm button, located on the left side of the track.