I LOVE both of these options, you can’t go wrong with either!
[name_f][/name_f][name_f]Rosemary[/name_f] [name_f]Louise[/name_f] “Rosie”[name_f][/name_f] – definitely my personal preference of the two! [name_m]The[/name_m] vibes here are perfect with your sibling set: sweet & friendly, with a bit of a southern feel. I love [name_f]Rosie[/name_f] as a nickname, and I think it really helps to bridge the gap between the vintage feminine [name_f]Rosemary[/name_f] & the slightly spunkier [name_f]Anne[/name_f] McCall. [name_m]The[/name_m] vibes: 
[name_f][/name_f] 
[name_f][/name_f] 
[name_f][/name_f] 
[name_f][/name_f] 
[name_f]Julia[/name_f] [name_f]Katherine[/name_f] “Julia Kate”[name_f][/name_f] – this option definitely feels a little more timeless, elegant & chic, with a little less of that spunky southern feel. [name_f]She[/name_f] still works well with her siblings, but I think a nickname like [name_m]Jules[/name_m] or [name_m]Kit[/name_m] might help to blend them a little better. [name_m]The[/name_m] vibes: 
[name_f][/name_f] 
[name_f][/name_f] 
[name_f][/name_f] 
I hope this helped, best of luck!