Correct me if I am wrong but starting in 1987 post Lindsey's departure, Stevie started to sing the second verse with Billy. She never did this before, correct? I have never seen her do this on a Rumours, Tusk, or Mirage tour. Stevie continued to do it again on the BTM and Farewell tour. My hunch is Stevie was adding some of her magic to not make it sound like a cover song in concert since it was a Lindsey song.
Once Lindsey came back, Stevie continued the tradition continued. I remember being surprised Stevie sung the second verse again when Lindsey came back for the Dance. I wonder if Stevie and Lindsey ever had a conversation about this. As much as Stevie hated the shacking up line, she started to sing it.
Just an interesting observation how Lindsey's departure changed the dynamic live in concert.
Here is a 1987 clip of Stevie taking the second verse with Billy 1987
https://www.youtube.com/watch?v=rg1XE_mLZP0
The Dance 1997
https://www.youtube.com/watch?v=p8Ojjn35kP8