"
Cecelia Casella" isn't the most fortunate euphony. But if you love the name that much you'll be sorry if you don't use it. It's kind of sing-songy, in a good way. :-)
By the way, I don't suppose I could talk you into the
Cecilia spelling. Since the name is the feminine form of
Cecil the
Cecilia spelling makes the most sense, to me at least. You can still use any spelling of a nn you'd like. Just a thought.
Or how about "
Celia Cassella" intead, with the same nn Celie? (
Cecilia and
Celia have two completely different origins/meanings, despite the similarity in sound. That's what accounts for the difference in spelling between the two.)