Here's the video I made ages ago (03/20/2017) showing how to use MultiRiffs in Biab, this is that same way it works now.
The Audio Track is your stereo master this is SOLOED,
each of the 7 tracks has the same instrument generated on the same bars,
you leave the Audio track SOLOED and then SOLO each of the 7 tracks 1 at a time until you find the riff you like.

Notice in the video it leaves the empty bar padding in the file to allow easy drag n drop and lined up correctly,
or if you just select those bar it will give that section without padding.
Watch https://www.dropbox.com/s/4es22n4a8gq9vku/BB-MultiRiffs.mp4?dl=0
Download https://www.dropbox.com/s/4es22n4a8gq9vku/BB-MultiRiffs.mp4?dl=1