I think Sophia and Skye go best with Ivy amd Amelie.
Violet is a flower name with a V sound so too similar to Ivy and leaving Amelie out.
Niamh also has that V sound so Amelie is left out again.
Suggestions:
Ivy, Amelie, and Eloise
Ivy, Amelie, and Beatrix
Ivy, Amelie, and Estelle
Ivy, Amelie, and Daphne
Ivy, Amelie, and Romy
Ivy, Amelie, and Cara
Ivy, Amelie, and Luna
Ivy, Amelie, and Elise
Ivy, Amelie, and Tess
Ivy, Amelie, and Celeste
Ivy, Amelie, and Grace
Ivy, Amelie, and Lara