I love [name_f]Adelaide[/name_f]! [name_f]Adelaide[/name_f] and [name_f]Rosalind[/name_f] would make a gorgeous sibset!
[name_f]Adelaide[/name_f] [name_f]Flora[/name_f]
[name_f]Adelaide[/name_f] Song
[name_f]Adelaide[/name_f] [name_u]Dove[/name_u]
[name_f]Adelaide[/name_f] [name_u]Marie[/name_u]
[name_f]Adelaide[/name_f] [name_u]June[/name_u]
[name_f]Adelaide[/name_f] [name_u]Truth[/name_u]
[name_f]Adelaide[/name_f] [name_f]Jane[/name_f]
[name_f]Adelaide[/name_f] [name_f]Opal[/name_f]
I really love [name_f]Adelaide[/name_f]!
Adelaide is gorgeous!
[name_f]Adelaide[/name_f] [name_u]Ruby[/name_u] and [name_f]Adelaide[/name_f] [name_f]Clara[/name_f] came to mind
[name_f]Adelaide[/name_f] is lovely! Beautiful, strong, and approachable. I think it pairs really nicely with your older daughter’s name, too. I’m not big on [name_f]Bonnie[/name_f] personally, but I do think it works with your sibset. I also love [name_f]Jane[/name_f], [name_f]Opal[/name_f], [name_f]Beatrice[/name_f], [name_u]Sage[/name_u], [name_f]Naomi[/name_f], and [name_f]Miriam[/name_f] from your list–of those, I’d say [name_f]Beatrice[/name_f] is my favorite with [name_f]Mabel[/name_f]. You have such a great list overall! 
Bonnie and [name_f]Mabel[/name_f] is a beautiful sibset!
I love [name_f]Adelaide[/name_f], [name_f]Opal[/name_f], [name_f]Rosalind[/name_f], [name_u]Sage[/name_u], and [name_f]Gwendolyn[/name_f] on your list!
Other ideas (Some go better with [name_f]Bonnie[/name_f]):
[name_u]River[/name_u]
[name_f]Claire[/name_f]
[name_f]Sophie[/name_f]
[name_f]Fleur[/name_f]
[name_f]Rosalie[/name_f]
[name_u]Louie[/name_u]
[name_f]Lucy[/name_f]
[name_u]Julie[/name_u]
[name_f]April[/name_f]
[name_u]Snow[/name_u]
[name_u]Sparrow[/name_u]
[name_f]Swan[/name_f]
[name_f]Violet[/name_f]
[name_f]Scarlett[/name_f]
[name_f]Wendy[/name_f]
[name_u]Sky[/name_u]
[name_u]Raven[/name_u]
[name_f]Odette[/name_f]
[name_f]Orchid[/name_f]
[name_f]Ondine[/name_f]
[name_f]Natalie[/name_f]
[name_f]Maple[/name_f]
[name_f]Lucy[/name_f]
[name_u]Kayden[/name_u]
C/Katherine
[name_f]Jade[/name_f]
[name_f]Iris[/name_f]
Hibiscus
[name_f]Hazel[/name_f]
[name_u]Holland[/name_u]
[name_f]Hallie[/name_f]
[name_f]Gizelle[/name_f]
[name_u]Evelyn[/name_u]
[name_u]Falcon[/name_u]
[name_f]Catelyn[/name_f]/Kaitlin
[name_u]Allison[/name_u]
[name_f]Candice[/name_f]
[name_f]Avalyn[/name_f]
[name_u]Avery[/name_u]
[name_f]Astrid[/name_f]
[name_f]Alouette[/name_f]
I don’t know if you like names then ends with O, but here’s a list if you do Girls names ending in O
Bonnie [name_f]Adeline[/name_f]
[name_f]Bonnie[/name_f] [name_f]Delilah[/name_f]
[name_f]Bonnie[/name_f] [name_f]Amelia[/name_f]
[name_f]Bonnie[/name_f] [name_f]Alice[/name_f]
[name_f]Bonnie[/name_f] [name_f]Aurora[/name_f]
Adelaide [name_f]Charlotte[/name_f]
[name_f]Adelaide[/name_f] [name_f]Genevieve[/name_f]
[name_f]Adelaide[/name_f] [name_f]Cordelia[/name_f]
[name_f]Adelaide[/name_f] [name_f]Cora[/name_f]
[name_f]Adelaide[/name_f] [name_f]Josephine[/name_f]
Mabel and [name_f]Adelaide[/name_f] are perfect together!
oo I really like both! [name_f]Mabel[/name_f] is lovely and both suit her.
[name_f]Do[/name_f] you like nicknames? Might help you decide as [name_f]Bonnie[/name_f] probably won’t have one where as [name_f]Adelaide[/name_f] has a few options ([name_f]Addy[/name_f], [name_f]Laidy[/name_f], [name_f]Daisy[/name_f], etc)
I prefer [name_f]Bonnie[/name_f] with [name_f]Mabel[/name_f] but [name_f]Adelaide[/name_f] is great too! [name_m]Just[/name_m] an idea - if you love [name_f]Adelaide[/name_f] but are worried about it being a proper noun, how about [name_f]Adeline[/name_f]? I think [name_f]Bonnie[/name_f] [name_f]Adeline[/name_f] is beautiful!
I’d also suggest [name_f]Bonnie[/name_f] [name_f]Gwendolyn[/name_f], [name_f]Adelaide[/name_f] [name_f]Opal[/name_f], [name_f]Bonnie[/name_f] [name_f]Camilla[/name_f] and [name_f]Adelaide[/name_f] [name_f]Miriam[/name_f]!
[name_f]Ingrid[/name_f] came to mind initially as another idea but maybe you’ll like these instead:
[name_f]Alice[/name_f]
[name_f]Josephine[/name_f]
[name_f]Ivy[/name_f]
[name_f]Iris[/name_f]
[name_f]Beatrix[/name_f]
[name_f]Clementine[/name_f]
[name_f]Edith[/name_f]
[name_f]Clover[/name_f] - mn, I love [name_f]Bonnie[/name_f] [name_f]Clover[/name_f]!
[name_f]Esther[/name_f]
[name_f]Lilac[/name_f] - mn
[name_u]Evelyn[/name_u]
[name_f]Primrose[/name_f] - maybe mn?
[name_f]Florence[/name_f]
[name_f]Juliet[/name_f]
[name_f]Emmeline[/name_f]
[name_f]Caroline[/name_f]
[name_f]Olive[/name_f] - mn?
[name_f]Millicent[/name_f]
[name_f]Hope[/name_f] a name here sparks something for you 
I like [name_f]Adelaide[/name_f] [name_f]Jane[/name_f] and [name_f]Adelaide[/name_f] [name_u]Sage[/name_u].
I like all of these combos but [name_f]Bonnie[/name_f] [name_f]Camilla[/name_f] is my favorite!
These are all pretty great, but [name_f]Adelaide[/name_f] Song, [name_u]Truth[/name_u], [name_f]Jane[/name_f], and [name_u]Dove[/name_u] are my favorite! [name_f]Rosalind[/name_f] was actually our top contender for awhile but it is pretty close to his sisters name, and we dont want to do honor names or similar names for family members that are still alive. We both really like the name so we might just go with it anyways though
Adelaide [name_f]Clara[/name_f] is super cute!
Thank you I love so many of these! [name_f]My[/name_f] favorites for [name_f]Adelaide[/name_f] are [name_f]Swan[/name_f], [name_f]Violet[/name_f], [name_f]Natalie[/name_f], [name_f]Gizelle[/name_f], [name_u]Evelyn[/name_u], and [name_u]Avery[/name_u]. I really like the O names you posted for [name_f]Bonnie[/name_f]–[name_f]Odette[/name_f], [name_f]Orchid[/name_f] and [name_f]Ondine[/name_f]–because her initials will be BOO and I was married on Halloween 
I also like [name_f]Bonnie[/name_f] [name_f]Avalyn[/name_f] a lot!
Love [name_f]Bonnie[/name_f] [name_f]Adeline[/name_f] and [name_f]Bonnie[/name_f] [name_f]Amelia[/name_f]!
I’m not too worried about nicknames but I’ve never heard [name_f]Daisy[/name_f] as a nickname for [name_f]Adelaide[/name_f]. Its super cute and works really well because I like the name [name_f]Daisy[/name_f] a lot but my husband does not like it as a given name
I prefer [name_f]Adeline[/name_f] but I love both names !!
Much prefer [name_f]Adelaide[/name_f] to [name_f]Bonnie[/name_f] which is getting increasingly popular here (UK/Ire)
Although i love [name_f]Adaline[/name_f] ( after the film Age of [name_f]Adaline[/name_f]) over [name_f]Adelaide[/name_f]
Echoing that [name_f]Bonnie[/name_f] and [name_f]Mabel[/name_f] would be perfect sisters. I really like [name_f]Bonnie[/name_f] [name_f]Sigrid[/name_f] from your names under consideration. It feels unexpected and I feel that combo gets away from the [name_f]Bonnie[/name_f] as an adjective issue.