I have it on very good authority that the scrapped set which included Back That Up, Candy Shop, 4 Minutes and Music was intended to follow DCFMA and was designed to be a dance off battle between M and the dancers. The whole act was scrapped after M got sick, she didn't have enough strength to perform this set as it was very dance-heavy. Frozen was scrapped right before Manchester, M apparently thought it felt too dark and depressive so she switched it to Rain which has more of an uplif