This is an update on how to create up a realtrack freezing sections that you want to keep and regenerating other sections, using the method above, you will be creating the track you need using up to 7 different sections using the F5 "Mute" or "Back to normal", so you keep the parts you like by setting the start of the section to default "......", the sections you don't want set the start of the section to "Mute" then "Back to normal if there's another section you want to keep.
The Muted sections will be generated on the other tracks, when done all the tracks will be merged to one track just how you want it or as near as can be.
I hope by Dec 2018 it won't be needed and this function will be implemented in BB19. !


Generate and solo the first section in track 1 to your liking then mute it with F5 where the good ends and Freeze the track.
Solo Track 2 (and Audio) Un-mute F5 at that bar, Generate the next section to your liking then mute it with F5 where the good ends and Freeze the track.
Solo Track 3 (and Audio) Un-mute F5 at that bar, Generate the next section to your liking then mute it with F5 where the good ends and Freeze the track.
Solo Track 4 (and Audio) Un-mute F5 at that bar......

Now mute the Audio Track and Drag Render the master to get your RealTrack.

Biab Track Injector for Reaper
Free Biab Chord Picker Tool