i wonder if M and C couldn't have had some sort of rehearsal prior? neither were especially busy at the time. and when you look at what the Miracles did, the Tops/Tempts and others, I wouldn't think those were all pulled of with just 20 mins of rehearsal that day.

also wouldn't they have already provided Diana with the charts and music for the medley? someone would have had to compose it and prepare it. it's not like it would have contained all sorts of odd things like Your Kiss of Fire, I Can't Make It Alone and Tears of Sorrow lol It would have probably had Stop, Baby Love, maybe you can't hurry love. all very commonly used songs, all songs she had been using in her shows for years.

and if the medley was prepared prior, couldn't she have been the one to say "no let's cut Back in my arms as I've not sung that for years." and she'd have been able to stick to songs she was comfortable with

heck - why didn't they just ask her for the arrangements of the latest medley she was using in her act? Mary and Cindy could easily have been given whatever backing vocals charts Diana was using.