The possibility of reconciling with Cinders' stepmother and stepsisters. Especially touching, if you know some variants of the original fairytale, where Cinderella's sisters have their heels and toes chopped off. Values Dissonance indeed.
Getting through to the sisters results not only in an improved relationship with Cinders, but also an improved understanding of themselves. This is reflected in the royal Ball — if you didn't get through to them, Gloria will be tongue-tied and break down from stress, and Sophia will be self-deprecating and venomous as usual. If you did, however, their interactions with Basile are much healthier and show they are growing out of their depressive state.