I prefer
Cecily. It still gives you the musical reference, and it looks and sounds neater and tidier. Though there is the
Simon and Garfunkel song ... I knew a car named
Cecilia once; it kept letting its owner down! And, unlike
Cecily,
Cecilia does have a rather whiney sound.
I prefer
Cecily Wilhelmina Stewart or
Cecily Augusta Stewart. And I think either sounds wonderful with
Theodora and
Hermione. If you asked
Theodora which she prefers, I wonder what she'd say. She's old enough to have preferences, which need not be binding on you.