I wouldn’t worry too hard about matching. I really think Allegria is a painful attempt to make it match length-wise. I wouldn’t try to force an all 4-syllable set. Maybe I’m saying it wrong, but I thought [name]Cordelia[/name] had three syllables anyway: Coar-deel-ya.
Is [name]Lina[/name] Lye-na or [name]Leena[/name]?
And I say [name]Cordelia[/name] with 4 syllables but it wasn’t necessarily to make them have the same amount of syllables it was just to have them all seem longer, I could have gone the [name]Claudiana[/name] route! Lol.
Its less about length and more about styles that match.
[name]Claudie[/name], [name]Lina[/name], [name]Thea[/name], [name]Allegra[/name] and [name]Belle[/name] - I think [name]Claudie[/name] and [name]Lina[/name] are cute, but too short/nickname-y for me. I love [name]Thea[/name] and [name]Belle[/name], and for me these work as full names, I love them I really, really dislike [name]Allegra[/name] though.
or
[name]Cordelia[/name], [name]Karolina[/name], [name]Theadora[/name], Allegria and [name]Mirabella[/name] - I love [name]Mirabella[/name] and [name]Theodora[/name]. Codelia is okay, as is [name]Carolina[/name]. Again, I hate Allegria.
My favourite set similar would be:
[name]Claudia[/name] or [name]Cecelia[/name]
[name]Caroline[/name]
[name]Theodora[/name]
[name]Mirabel[/name]
[name]Adeline[/name]
I just want to make it one name - [name]Allegra[/name] [name]Mirabelle[/name]!
I think you could get away with [name]Allegra[/name], [name]Cordelia[/name], and [name]Mirabella[/name] as siblings, though I like [name]Allegra[/name], [name]Cordelia[/name], and [name]Miranda[/name] better. [name]Allegra[/name], [name]Viola[/name], and [name]Carina[/name] would be beautiful, too!