hi, basically you need to load a Kontakt instrument for each track and assign a midi channel for each track, according to this tutorial:

http://www.pgmusic.com/tutorial_garritan.htm

the bad news is that you would have to do that for each BB song....not very practical, so a better option is to save a few generic Kontakt setup for each genre, for example load instruments for a rock setup, then save, then load the ones for a jazz setup ,save , etc, so you will be using 5 or 6 setups only according to the genre.