The Dazzlings lost most of their power with the shattering of their gems at the end of the Battle of the Bands. But Adagio has managed to recover a small part of that power to command, and uses it to manipulate the bodies of herself and her band mates.

Chapter 1) Adagio gains a penis and proceeds to expand it to inhuman proportions
(penis expansion)

Chapter 2) Adagio has sex with an expanding Sonata Dusk
(penis, height, breast, and ass expansion)

Chapter 3) Adagio and Sonata go to work on Aria Blaze
(as above + muscle growth)