The Sea Witches appear only in the first novel. They are mentioned leaning over their violins preparing for the Autumn Concert at Dragon Hall.
- They were introduced in Chapter 2, A Wily Thief... of the Isle of the Lost: A Descendants Novel.
- They play violins in the Junior Orchestra at Dragon Hall.
- In Rise of the Isle of the Lost: A Descendants Novel Uma is the only one of the main three characters (Uma, Gil and Harry) without confirmed siblings. This could indicate Uma is an only child and these Sea Witches are her cousins by her aunt Morgana.