I like [name_f]Stella[/name_f] [name_f]Vivienne[/name_f] with [name_f]Scarlett[/name_f] and [name_u]Beau[/name_u]. [name_m]Even[/name_m] [name_f]Stella[/name_f] [name_f]Grace[/name_f] would sound musical too
With your surname and sibling names my pick is [name_f]Leila[/name_f], with either [name_f]Grace[/name_f] or [name_f]Vivienne[/name_f] in the middle. [name_f]Leila[/name_f] is sleek and smart and would work very well.
I prefer [name_f]Vivienne[/name_f] [name_f]Grace[/name_f], but I wonder if it sort of rhymes with your last name, given the fact that it ends with -ian? Depending on the pronunciation, it might. In which case, I’d prefer [name_f]Stella[/name_f] [name_f]Vivienne[/name_f].
Stylistically, I think [name_f]Stella[/name_f] or [name_f]Vivienne[/name_f] is the best fit with [name_f]Scarlett[/name_f] & [name_u]Beau[/name_u].
I will note though that [name_u]Vivien[/name_u] [name_u]Leigh[/name_u] played [name_f]Scarlett[/name_f] O’Hara in Gone with the Wind – definitely not necessarily a dealbreaker, but I thought it worth mentioning just in case that association might potentially bother you for daughters/sisters called [name_f]Scarlett[/name_f] & [name_f]Vivienne[/name_f].
Leila!! Goes with other siblings nicely and is a pretty name.
Both middles work with the name too but slightly prefer [name_f]Grace[/name_f].
[name_f]Leila[/name_f] [name_f]Grace[/name_f].
[name_f]Isabelle[/name_f] [name_f]Grace[/name_f].
Sc@rlett and Is@belle would make great sister names together. Sc@rlett, Be@u and Is@belle. Together they have the same style. When you say the names aloud they flow well. When written together, I like how all three use only the vowels E and A. That gives a certain visual continuity to the names. The girls names have the same number of letters and have repeating consonants. Those are the little things I notice. [name_f]Hope[/name_f] it’s helpful. Good luck with your decision.