Hi Boots,
I think that part of your problem is due to the track's freezing. It's possible that the pedal steel could have been frozen when the song has less bars than what it does now.
When I get something I like, I do exactly what you have done and freeze the parts I want to keep.
Then I save the song.
Then I save the song with a slightly new name.
With this newly named version I unfreeze the track(s) and regenerate. (Because I've already saved the song with the previous name, I can always get back to it and save anything from it that I've frozen.)
I usually end up with around 10-15 versions of a song I can return to if I want to. To change the name, I just use a number. For example, if my song is called "MySong", I first save it as "MySong1", then when I save and move to more experimenting, it becomes "MySong2", then "MySong3", etc.
BIAB files are not very big (usually around 20-30 kilobytes) so they don't take up much room on the computer.
Following this plan of attack, I usually regenerate my song around 1,000 (estimated) times during its writing. This gives me a chance to hear tons of generations and often there is an even better one waiting to be found.
Regards,
Noel