[name_f]Summer[/name_f] or [name_f]Scarlett[/name_f] are great with [name_f]Caroline[/name_f]!
I like the suggestion of [name_f]Birdie[/name_f] as well. Maybe [name_f]Lucille[/name_f] or [name_f]Lucinda[/name_f] would work, if not [name_f]Lucy[/name_f]?
[name_u]Love[/name_u] [name_f]Violet[/name_f] with [name_f]Caroline[/name_f]! I also really like [name_f]Summer[/name_f]. Don’t find dated more like modern classic.
[name_f]My[/name_f] fave is [name_f]Scarlett[/name_f]. I do find [name_f]Summer[/name_f] and [name_f]Cassidy[/name_f] dated (moreso Cassidy) but also just very different in vibe to [name_f]Caroline[/name_f]. I don’t think sibling names have to be perfectly uniform in that sense but I do find those jarring. The similar [name_f]Cassia[/name_f] would work well with [name_f]Caroline[/name_f], as long as you don’t mind same starting sound which you obviously don’t. I’ve never liked [name_f]Violet[/name_f] as it’s too much like violent for me, but I’m very much in the minority and do think it would go well. [name_f]Scarlett[/name_f] is lovely.