Hi,

I'm not sure what you mean by split. Do you mean cut the track at a particular location (shortcut T) and then move one of the pieces to another track? Or do you mean that you want part, say the base part on one track and the treble on another? If so, then copy the object to another track (Ctrl+drag with the left mouse button). Open the MIDI piano roll for each and delete the notes that you don't want from each object. Don't forget to give the second track an instrument.