Thanks to a head's up from one of Poppet & Posies readers (thank you, EsDolls!), I was able to find an image of the book cover for Melody's second book, Never Stop Singing.
This confirms that Melody's Flower Peplum Dress is part of her collection. Accessories seem to be off-white or pale beige sandals and a pink hair bow!
But the cover also could be clues to other accessories in Melody's collection--a microphone and stand! While a drum set or piano is possible as well, I would not be certain how well those would sell, especially if Melody is primary a singer and not an instrumentalist.