I'd also recommend reaper but it depends how comfortable you are with using software.

What form do the dozen takes exist in? And what were they recorded on?

And perhaps a silly question...

Have you listened to them?

If you have heard them could you not just do it manually and say 'verse 1 and verse 4 from example one's etc?

Would you split in smaller chunks - like line by line?

If they are all the same length I'd put each version on a separate track on reaper and then start listening. Then copy and paste onto a final track.

How much of a rush are you in?