I like [name_f]Alice[/name_f] - simple, sweet and stylish - and gives her an initial of her own.
However, I also really like [name_u]Vivian[/name_u] and the way it has a V like [name_u]Evan[/name_u] and [name_m]Harvey[/name_m] and ‘-an-’ like [name_f]Joanna[/name_f] 
Congratulations!
I absolutely love [name_u]Vivian[/name_u] & [name_f]Juliet[/name_f] 
However with your sibling set my favourite is definitely [name_u]Vivian[/name_u]. [name_u]Vivian[/name_u] is strong, tailored, classic, has the lovely meaning ‘life’ and I like that she would have her own individual initial within your sibling set. The overall sibling set [name_u]Evan[/name_u], [name_m]Harvey[/name_m], [name_f]Joanna[/name_f] & [name_u]Vivian[/name_u] looks really well put together with lots of repeated V and A sounds working well with the boys but has the same classic vibe of [name_f]Joanna[/name_f]. [name_f]Lovely[/name_f] option.
[name_f]Juliet[/name_f].
[name_f]Alice[/name_f]! I love her and how [name_f]Alice[/name_f] fits beautifully with the others, plus your children would all have their own initial.
[name_u]Evan[/name_u], [name_m]Harvey[/name_m], [name_f]Joanna[/name_f] and [name_f]Juliet[/name_f] flows the nicest in my opinion. [name_f]My[/name_f] second vote would be for [name_f]Alice[/name_f]
I do like [name_f]Violet[/name_f]. Great suggestion!
Congratulations @Britby72 !!
[name_f]Alice[/name_f] , [name_u]Vivian[/name_u] and [name_f]Juliet[/name_f] are simply stunning! They all feel classic with a royal or literary flair!
With [name_u]Evan[/name_u], [name_m]Harvey[/name_m] and [name_f]Joanna[/name_f] my choice would be [name_f]Alice[/name_f]. [name_f]Alice[/name_f] would give each kid their own unique initial . [name_f]My[/name_f] fear with [name_u]Vivian[/name_u] would be that [name_f]Joanna[/name_f] would have the only name without a V . [name_f]Juliet[/name_f] is beautiful and I love it as a sister to [name_f]Joanna[/name_f] but I do think (for me anyway) I would be constantly mixing them up
Thank you, and thanks for the great suggestions! I really love [name_f]Clara[/name_f] and [name_f]Naomi[/name_f], but we recently had people close to use use those names for their children. I also really like [name_f]Adeline[/name_f], [name_f]Margot[/name_f], and [name_f]Scarlett[/name_f]!
Thank you! I do already mix up the three of them - I assume it will only get worse with four. 
I like [name_f]Juliet[/name_f] spelled this way. The girls’ names will each have six letters.
Ev@n, H@rvey, Jo@nna and [name_f]Juliet[/name_f]
[name_f]Juliet[/name_f] is my favorite! 
[name_u]Vivian[/name_u] would come in second place, only it blends in a little too much with Evan’s name. I’m not really a fan of [name_f]Alice[/name_f], personally, but she does have the benefit of having her own letter to set her apart from her siblings. 
I like them all but I have a soft spot for [name_u]Vivien[/name_u] over [name_u]Vivian[/name_u] because I think it appears more like a name meant for a girl when it is spelled with the e. so for that reason I’m gonna say [name_f]Alice[/name_f] and [name_f]Juliet[/name_f] seem like good top contenders over [name_u]Vivian[/name_u] and then between those 2 [name_f]Alice[/name_f] is a much better fit with siblings named [name_f]Joanna[/name_f], [name_u]Evan[/name_u], and [name_m]Harvey[/name_m]. Those 4 names together are cohesive and more on the simple side, not too frilly or dramatic. And [name_f]Joanna[/name_f] has always been plainly female in my head but at the same time it is not an overtly girly-girl name while steering clearly away from being a tomboyish name at the same time, and so a sister named [name_f]Alice[/name_f] keeps that same theme rather than a sister named [name_f]Juliet[/name_f] which would honestly stand out from the bunch of them because it’s just so romantic & dramatic sounding. Still, both are great names whatever you ultimately choose to go with.
I couldn’t help but come up with some middle names for [name_f]Alice[/name_f] though.
[name_f]Alice[/name_f] [name_u]Greer[/name_u]
[name_f]Alice[/name_f] [name_f]Susan[/name_f]
[name_f]Alice[/name_f] [name_u]Dean[/name_u]
[name_f]Alice[/name_f] [name_u]Mallory[/name_u]
[name_f]Alice[/name_f] [name_f]Bridey[/name_f]
[name_f]Alice[/name_f] [name_u]Maven[/name_u]
[name_f]Alice[/name_f] [name_f]Fiorella[/name_f]
I vote [name_f]Alice[/name_f] but love all 3 choices! [name_m]Even[/name_m] though they may be similar sounds to sibling names I think you can’t go wrong:)
I think [name_f]Alice[/name_f] fits best with your other kids! [name_u]Evan[/name_u], [name_m]Harvey[/name_m], and [name_f]Joanna[/name_f] all feel very sweet and down to earth. I think [name_f]Alice[/name_f] goes nicely with them!
[name_f]Juliet[/name_f] fits perfectly!
[name_u]Love[/name_u] the idea of a little [name_f]Alice[/name_f] as a sister to [name_u]Evan[/name_u], [name_m]Harvey[/name_m], and [name_f]Joanna[/name_f]! She’s super sweet. I also love [name_u]Vivian[/name_u] though, and [name_u]Evan[/name_u], [name_m]Harvey[/name_m], [name_f]Joanna[/name_f], and [name_u]Vivian[/name_u] would be really lovely. Either of those gets my vote!
[name_f]Alice[/name_f]!
[name_u]Ever[/name_u] so slight preference for [name_f]Juliet[/name_f] if I had to pick, but all three options are lovely, you can’t go wrong!
Also I love that you have a [name_m]Harvey[/name_m]! So cute
All of your options are so lovely, but I think my favorite is [name_f]Juliet[/name_f]. So warm and charming but ages so well. I don’t think the initial sharing is a problem, since it’s just between the two girls so looks more like an intentional pattern than lack of originality. [name_u]Vivian[/name_u] is my second choice and [name_f]Alice[/name_f] is my third – for some reason, I don’t love [name_f]Alice[/name_f], even though I should in theory since it’s very much in line with my taste!
With siblings, I like [name_f]Alice[/name_f]!