We are expecting another little girl in [name]May[/name]. She will be joining big sister [name]Sylvie[/name]. What do you think of [name]Vivienne[/name] nn [name]Vivi[/name]? Has it become to popular? We like [name]Sylvie[/name]'s name because it is still unique.
I love [name]Sylvia[/name] nn [name]Sylvie[/name]! I think [name]Vivienne[/name] is way too close to [name]Sylvia[/name], though, especially if you’re going to be calling her [name]Vivi[/name]. What about:
[name]Miriam[/name]
[name]Helena[/name]
[name]Caroline[/name]
[name]Rosemary[/name]
[name]Alice[/name]
[name]Penelope[/name]
[name]Margaret[/name]
[name]Theodora[/name]
[name]Anneliese[/name]
[name]Clara[/name]
[name]Eloise[/name]
[name]Fiona[/name]
[name]Louisa[/name]
[name]Adeline[/name]
[name]Elodie[/name]
[name]Juliet[/name]
[name]Charlotte[/name]
I think [name]Vivi[/name] and [name]Sylvie[/name] are too similar for sisters.
Others:
[name]Elinor[/name]
[name]Louisa[/name]
[name]Evelyn[/name]
[name]Vera[/name]
[name]Frances[/name]
[name]Clara[/name]
[name]Fiona[/name]
I don’t think [name]Vivian[/name] is too close to [name]Sylvia[/name], but I do think the nn’s sound kind of close. I like the repeated “v” though. I think it’s a cute connection.
What about:
[name]Violet[/name] (nn [name]Vi[/name])
[name]Evelyn[/name] (nn [name]Evie[/name])
[name]Genevieve[/name]
[name]Lavender[/name]
Ladies thank you for the feedback. I didn’t even think of the connection of [name]Sylvie[/name] and [name]Vivi[/name] sounding so close. I liked your suggestions especially [name]Vera[/name], [name]Violet[/name], [name]Frances[/name], and [name]Eloise[/name]. We also have been contemplating [name]Matilda[/name] nn [name]Tilly[/name]. Back to the drawing board.
[name]Love[/name] [name]Sylvia[/name] nn [name]Sylvie[/name]. I think [name]Sylvie[/name] and [name]Matilda[/name] nn [name]Tilly[/name] is very sweet.
Some suggestions…
[name]Margaret[/name] nn [name]Maisie[/name]*
[name]Charlotte[/name] nn [name]Lottie[/name]
[name]Elizabeth[/name] nn [name]Libby[/name]
[name]Katherine[/name] nn [name]Kitty[/name]
[name]Florence[/name] nn [name]Flossie[/name]
[name]Rosalind[/name] nn [name]Rosie[/name]*
[name]Ada[/name]
[name]Eleanor[/name] nn [name]Nellie[/name]
[name]Beatrix[/name] nn [name]Trixie[/name]
[name]Hazel[/name]
[name]Lydia[/name] nn [name]Lydie[/name]* ([name]Sylvia[/name] and [name]Lydia[/name] is a nice connection with the y’s imo, but it may be too close)
[name]Harriet[/name] nn [name]Hattie[/name]
[name]Louisa[/name] nn [name]Lulu[/name]*
[name]Josephine[/name] nn [name]Posey[/name]*
[name]Sarah[/name] nn [name]Sally[/name]
[name]Cordelia[/name] nn [name]Cordy[/name]
[name]Georgia[/name] nn [name]Gigi[/name]*
[name]Cecilia[/name] nn [name]Celie[/name] (or, [name]Cecily[/name] nn [name]Cissy[/name])
[name]Millicent[/name] nn [name]Millie[/name]
[name]Jane[/name] nn [name]Janie[/name]
*'d my faves. Sorry for repeats 
Have you made a decision? We’re in the same exact predicament - daughter [name]Sylvia[/name] (nn [name]Sylvie[/name]) and another girl due in [name]June[/name]. [name]Vivian[/name] (spelled this way, probably nn [name]Vivi[/name] or [name]Viv[/name]) is our first choice, even after reading this post, but I still fear it’s too matchy. The only other name we can currently agree on is [name]Freya[/name], but I worry that’s too unusual. Argh!
Oh! I was just gonna suggest [name]Freya[/name]! I think it’s an awesome name! I aslo like other suggestions of [name]Evelyn[/name]!
I think [name]Sylvia[/name] and [name]Vivian[/name]/[name]Vivienne[/name] are gorgeous together, and though the nicknames are similar, they aren’t too close, in my opinion. Really stunning names! Others I like with [name]Sylvia[/name]:
[name]Louisa[/name]
[name]Julia[/name]
[name]Lydia[/name]
[name]Liliana[/name]
[name]Eliana[/name]
[name]Helena[/name] nn [name]Leni[/name]
Good luck!