[name_u]Baby[/name_u] girl due here in a few months! Her big sister is [name_f]Violet[/name_f], big brother is [name_u]Atlas[/name_u]. Here are a few we are considering, please let me know your faves!
[name_f]Celeste[/name_f]
[name_f]Summer[/name_f]
[name_u]Skylar[/name_u]
[name_f]Phoebe[/name_f]
[name_f]Lyla[/name_f]
[name_f]Chloe[/name_f]
Big brother & sister have beautiful names! 
[name_f]Summer[/name_f] & [name_f]Phoebe[/name_f] are my favorites, they would fit in so nicely! 
I think [name_f]Phoebe[/name_f] would fit in great with [name_f]Violet[/name_f] and [name_u]Atlas[/name_u]! I also like [name_f]Celeste[/name_f].
I love [name_f]Celeste[/name_f]!
I’m really loving how [name_f]Violet[/name_f], [name_u]Atlas[/name_u] and [name_f]Celeste[/name_f] sound and look together. How stunning.
I also love [name_f]Phoebe[/name_f] and [name_u]Skylar[/name_u].
[name_f]Summer[/name_f] or Phoebe!!
Loooove [name_f]Phoebe[/name_f]! As a name on her own and with your two! That’s so so gorgeous. I think that’s my favorite pick from your list, and [name_f]Celeste[/name_f] is second. 
More ideas…
[name_f]Felicity[/name_f]
[name_f]Harriet[/name_f]
[name_f]Beatrice[/name_f]
[name_f]Tallulah[/name_f]
[name_f]Rhiannon[/name_f]
[name_u]Clare[/name_u]
[name_f]Imogen[/name_f]
[name_f]Willa[/name_f]
[name_f]Opal[/name_f]
[name_f]Odette[/name_f]
[name_f]Calla[/name_f]
[name_f]Nell[/name_f]
[name_f]Ruthie[/name_f]
[name_u]June[/name_u]
[name_f]Violet[/name_f] and [name_u]Atlas[/name_u] are wonderful!!
I really enjoy [name_f]Celeste[/name_f] and [name_f]Phoebe[/name_f] for you!!
[name_f]Lyra[/name_f] would be nice too!
Congrats 
[name_u]Love[/name_u] [name_f]Violet[/name_f] & [name_u]Atlas[/name_u]!
From your list I think [name_f]Phoebe[/name_f] has the right spirited energy of [name_f]Violet[/name_f] & [name_u]Atlas[/name_u]. [name_f]Phoebe[/name_f] belongs in this sibling set. I also think [name_f]Lyla[/name_f] (prefer Lila) and [name_f]Summer[/name_f] is perfect for this sibling set.
Some other ideas could be [name_f]Stella[/name_f], [name_f]Lyra[/name_f], [name_f]Elodie[/name_f], [name_f]Hebe[/name_f], [name_u]Fern[/name_u] and [name_u]Ruby[/name_u].
Good luck
[name_f]Phoebe[/name_f]!
[name_f]Celeste[/name_f] just immediately jumped out at me! I absolutely love the imagery of [name_f]Violet[/name_f], [name_u]Atlas[/name_u], and [name_f]Celeste[/name_f]. [name_f]Celeste[/name_f] just flows and fits in with [name_f]Violet[/name_f] and [name_u]Atlas[/name_u] perfectly
[name_f]My[/name_f] second would be [name_f]Lyla[/name_f], but I like [name_f]Lila[/name_f] better, and I feel like [name_f]Lila[/name_f] would look better than [name_f]Lyla[/name_f] with [name_f]Violet[/name_f] and [name_u]Atlas[/name_u] as well.
I like the sound of [name_f]Violet[/name_f], [name_u]Atlas[/name_u] and [name_u]Skylar[/name_u] the best followed by [name_f]Summer[/name_f]! You have some great choices 
I second [name_f]Lyra[/name_f]!
[name_f]Phoebe[/name_f] or [name_f]Lyla[/name_f] are lovely with [name_f]Violet[/name_f] and [name_u]Atlas[/name_u] and fit best in my opinion. [name_f]Summer[/name_f] seems a bit much to me - another nature word name - and [name_f]Celeste[/name_f], [name_u]Skylar[/name_u] and [name_f]Chloe[/name_f] feel different in style.
Congratulations!
[name_f]Lyla[/name_f] is my favorite, followed by [name_f]Celeste[/name_f]. Congratulations!
[name_f]Phoebe[/name_f] or [name_f]Lyla[/name_f]!
[name_m]Hi[/name_m] there.
I love [name_f]Violet[/name_f] & [name_u]Atlas[/name_u]!
Here is my favorite to least favorite from your list-
Summer-I’m loving this name lately. It’s so sunny, but feels warm & down to earth at the same time. It’s nature-y, but not in your face nature-y. Similar to [name_f]Violet[/name_f] & [name_u]Atlas[/name_u] in that regard. It’s easy & well known, but not very popular.
Phoebe-This is fun. [name_f]Cheerful[/name_f] & a little quirky & vintage but not stuffy. Totally similar style as [name_f]Violet[/name_f]. And then a little celestial like [name_u]Atlas[/name_u].
Chloe-It’s not my super favorite, but I like it. It sounds really pretty said out loud. Maybe it just seems sort of modern for my tastes. It does go well w/your kids’ names.
Lyla-I would have put this ahead of [name_f]Chloe[/name_f] if I weren’t so picky about spellings. I really need [name_f]Lila[/name_f]. The ‘y’ looks off to me. But it’s nice said out loud. The only thing is that maybe it’s kind of a tongue twister said with [name_f]Violet[/name_f]. But that’s not a deal breaker.
Celeste-I think that the style goes well with your crew. And it’s an interesting choice. It just sounds serious to me. Not as cheerful & spunky as [name_f]Violet[/name_f] & [name_u]Atlas[/name_u]. I also think that it shares a lot of the same sounds at [name_u]Atlas[/name_u]. Again, not a deal breaker. [name_m]Just[/name_m] something to consider.
Skylar-I think that just [name_u]Skye[/name_u] would be lovely here, but [name_u]Skylar[/name_u] feels trendy & I kind of prefer it (spelled Schuyler) for a boy.
[name_f]Hope[/name_f] this helps. 
[name_u]Skyler[/name_u] & [name_f]Phoebe[/name_f] are favorites from your list!
[name_f]Violet[/name_f], [name_u]Atlas[/name_u], & _______:
[name_f]Octavia[/name_f]
[name_f]Emmeline[/name_f]
[name_u]Romilly[/name_u]
[name_f]Tabitha[/name_f]
[name_f]Leona[/name_f]
[name_f]Estelle[/name_f]
[name_f]Talia[/name_f]
[name_f]Soleil[/name_f]
Delia/Cordelia
[name_m]Calyx[/name_m]
[name_f]Olympia[/name_f]
[name_f]Tamsin[/name_f]
[name_u]Sydney[/name_u]
[name_u]Blair[/name_u]
[name_u]Cassidy[/name_u]
[name_u]Delaney[/name_u]
[name_f]Elowyn[/name_f]
[name_f]Bronwyn[/name_f]
[name_u]Phoenix[/name_u]
[name_f]Daphne[/name_f]
[name_f]Delta[/name_f]
Magnolia/Nola
[name_f]Gemma[/name_f]
[name_f]Siena[/name_f]
[name_f]Raquel[/name_f]
[name_f]Elora[/name_f]
[name_f]Imogene[/name_f]
[name_f]Uma[/name_f]
[name_u]Bellamy[/name_u]
[name_f]Farrah[/name_f]
[name_f]Violet[/name_f], [name_u]Atlas[/name_u] and [name_f]Celeste[/name_f] or [name_f]Violet[/name_f], [name_u]Atlas[/name_u] and [name_f]Lyla[/name_f]!
If you’re planning on more kids, I would be careful about picking another word name. Two is a coincidence, but three starts to sound like a theme.
If this is your last babe and you’re not worried about keeping up themes, [name_f]Phoebe[/name_f] is my favorite in your set! I also really like [name_f]Celeste[/name_f]. [name_f]Chloe[/name_f], [name_f]Lyla[/name_f], and [name_u]Skylar[/name_u] drag the set more trendy-sounding, while [name_f]Celeste[/name_f] sounds more timeless.