I think [name]Eloise[/name] (and the similar [name]Elodie[/name]) is beautiful but it seems like you are in love with [name]Sylvie[/name]. I like [name]Sylvie[/name] [name]Juliet[/name] a lot. I agree that [name]Adele[/name] makes it sound like [name]Sylvia[/name] [name]Dell[/name].
Trying to suggest some more middles…
French:
[name]Cosette[/name]
[name]Delphine[/name] (also a flower)
[name]Corinne[/name]
Regine
[name]Fleur[/name]
[name]Sandrine[/name]
[name]Georgette[/name]
[name]Felice[/name]
[name]Mireille[/name]
[name]Seraphine[/name]
[name]Therese[/name]
[name]Camille[/name]
[name]Blanche[/name]
[name]Louise[/name]
[name]Mathilde[/name]
A names with three syllables - I think if you are going with an “a” middle, you should avoid one that starts with an “uh” sound for the [name]Sylvia[/name] problem, like [name]Adele[/name].
[name]Adelaide[/name] - also French
[name]Aurelia[/name] (love!) or the French - [name]Aurelie[/name]
[name]Amelie[/name] - French
[name]Amandine[/name] - French
[name]Anais[/name] - French
[name]Abigail[/name]
[name]Annabelle[/name]
[name]Aurora[/name]
These three might be too much “v” but I’ll throw them in…
[name]Aveline[/name] - French
[name]Avalon[/name]
[name]Avery[/name]