[name]Violet[/name] - great with [name]Sophie[/name], hope your husband can come around. [name]Vi[/name], [name]Vivi[/name], [name]Etta[/name], [name]Ettie[/name] are cute nns with [name]Sophie[/name], too, if you like nns. [name]Vivienne[/name]?
[name]Ruby[/name] - works with [name]Sophie[/name], but too me a LOT punchier and a lot of ee endings. But OK.
[name]Hazel[/name] - an interesting contrast to [name]Sophie[/name]. Somehow, [name]Hazel[/name] is made more youthful by [name]Sophie[/name] and [name]Sophie[/name] is made more mature by [name]Hazel[/name]. I like it! Can see nns [name]Hallie[/name] and [name]Ellie[/name].
What is the name regret with [name]Sophie[/name] [name]Scarlett[/name]? It’s quite pretty. Too popular? Too many S’s? I hope you can recover : ). I like it. If the issue is too popular than some of the nicknames here may be drawbacks, although most of them are not so obvious as to be automatic. If popularity is good, then the popular nns might be selling points.
[name]Genevieve[/name] - a beautiful name that is nicely French with [name]Sophie[/name]. Can you get over [name]Jenny[/name]? I know it was super popular in the 80s with [name]Jennifer[/name] but it really is a name with some solid English usage history. Alternately, would your husband and you be willing to nickname [name]Genevieve[/name] [name]Evie[/name] or [name]Neve[/name] or [name]Vivi[/name]?
[name]Adelaide[/name] - I also really like this with [name]Sophie[/name]. [name]Addie[/name]?
[name]Elisabeth[/name] - such a pretty, soft classic; I like this spelling with [name]Sophie[/name] a lot and I think this spelling is becoming much more standard than it used to be. INFINITE nickname possibilities, almost, [name]Ellie[/name] and [name]Lily[/name] being the really popular ones.
[name]Poppy[/name] - this is really cute and doable, but it seems much more like a nickname than [name]Sophie[/name] does. [name]Sophie[/name] and [name]Penelope[/name] works (Greek connection) and I’d really recommend you consider that. [name]Hazel[/name] hits some of the nature tones and works better, I think.
[name]Willow[/name] - is a lovely name, but doesn’t really sound like [name]Sophie[/name]'s sister to me if that matters to you. [name]Hazel[/name] hits some of the nature tones and works better. [name]Willa[/name] could work with [name]Sophie[/name] better too, I think, and I think you could nn her [name]Willow[/name].
[name]Finn[/name] - for me, this is fine with [name]Sophie[/name]! Shares her popularity, but it is trendier, I’d say. Grounded enough by some Irish traditions, though.
[name]Oliver[/name] - lovely with [name]Sophie[/name]! Only a step away from French [name]Olivier[/name], and a good match in terms of popularity-but-groundedness.
[name]Asher[/name] - I like it, it works. Another nature-y name from the wood ash. A bit Biblical with [name]Sophie[/name], but again that makes it somewhat popular-but-grounded.
[name]Rowan[/name] - I love this name but very Welsh next to [name]Sophie[/name], and I think becoming more popular for girls? I love that the O ties them together, though. [name]Owen[/name]?
[name]William[/name] - like this a lot!
Good luck!