I have just upgraded from Reason 3 to Reason 5 (I know, I'm behind the times but I like programs that work).
In Reason 3, I would import a MIDI file (which I create with an external sequencer) then create instruments. Then I would assign the tracks to instruments. Should I need to change the tracks (a frequent need!), I could delete the tracks without deleting the instruments. After reimporting the MIDI file, I would again assign the tracks to the already existing instruments.
In Reason 5, importing a MIDI file causes a combinator to be created automatically for every track. I can set up the combinators or replace them directly with other instruments. Should I wish to change the tracks, I can delete them without deleting the instruments, but when I reimport the MIDI, new combinators are created.
How I can assign the tracks to the already existing instruments?