Profbob:

This won't likely be any help since you're using 2012, but BIAB now has a "Song Form" function. You just say:

- A starts at Bar 1 for 4 bars
- B starts at Bar 5 for 4 bars
(etc. if you want more)

Then you just say, play my song like this:

AABBAA

That way you can revise how A and B play without any copying or pasting. You can try to find it in 2012 but I think it appeared in 2013.

Good luck!
LLOYD S