I would so appreciate your help as we are having a terrible time naming our new little girl. I love the name [name]Sylvie[/name]/[name]Sylvia[/name], but fear it is way too close to big sister’s name. [name]Stella[/name] has always been a favorite, but is it becoming too popular? [name]Elizabeth[/name] is a family name. Here are our frontrunners. Any advice/input/ideas are welcome. Thanks in advance!
[name]Lucia[/name] [name]Josephine[/name]
[name]Lucia[/name] [name]Elizabeth[/name]
[name]Stella[/name] [name]Elizabeth[/name]
[name]Stella[/name] [name]Lucia[/name]
[name]Laurel[/name] [name]Elizabeth[/name]
[name]Laurel[/name] [name]Lucia[/name]
[name]Sylvie[/name] [name]Elizabeth[/name]
[name]Sylvia[/name] [name]Monroe[/name]
I love [name]Lucia[/name] [name]Elizabeth[/name]! And [name]Lucia[/name] is so much more interesting than [name]Lucy[/name], which is a bonus!
And I think that [name]Cecilia[/name] and [name]Lucia[/name] sound lovely together. 
Generally, I think all your names are fine and sound good with the suggested mn. However, I think [name]Sylvia[/name]/[name]Sylvie[/name] or [name]Lucia[/name] are the best choices with [name]Cecilia[/name] as a sibset. Although they have [name]Roman[/name]/Latin roots too, [name]Stella[/name] and [name]Laurel[/name] have kind of a different feel than [name]Cecilia[/name] to me.
Some other similar sounding [name]Roman[/name]/Latin names you might like:
[name]Camille[/name]/[name]Camilla[/name]
[name]Julia[/name]
[name]Justine[/name]
[name]Lavinia[/name]
[name]Leticia[/name]
[name]Luciana[/name]
[name]Lucretia[/name]
[name]Marcella[/name]
[name]Minerva[/name]
[name]Miranda[/name]
[name]Mirabel[/name]
[name]Octavia[/name]
[name]Priscilla[/name]
[name]Regina[/name]
[name]Sabina[/name]
[name]Veronica[/name]
[name]Victoria[/name]