If I exactly understand your wishes, it can be done using only BK...

further more if you want to use the Vocal Phrases during an SMF playback,
you can setup the SMF to recall the Audio Keys Set and insert using sequencer, on track 13, MIDI note event to trigger the single Phrase.

If you want to use the Audio Keys during a Rhythm, you can use the Performance to recall Rhythm and the Audio Key... then there are some sync options between rhythm and audio-key both for start stop and for keeping sync together and avoid time derivation... try to read the OM ,
but as Diki suggested, only when putting hands on the instrument it will be easy to understand all features....

p.s. you can also record only one vocal wave file, then "cut" several phrases on the same file, because the cut is not a real wave file cut, but only a cue point (start,stop with several loop options), so you can create several phrase on the same wav file...
once again...easier to do than to be explained