Your kids have lovely names 
Of your options, I really like:
[name_f]Daphne[/name_f] [name_f]Juliet[/name_f] → vintage, literary and charming
[name_f]Daphne[/name_f] [name_f]Allegra[/name_f] → I like how [name_f]Allegra[/name_f] gives a similar vibe to Oscar’s middle
[name_f]Guinevere[/name_f] [name_f]Ivy[/name_f] → sleek and pretty
[name_f]Athena[/name_f] [name_f]Rosemary[/name_f] / [name_f]Clementine[/name_f] → warm, stylish and strong at the same time
[name_f]Juniper[/name_f] (Maxine) → bright, botanical, and fresh feeling, with the grounding nature of [name_f]Maxine[/name_f].
[name_f]Beatrix[/name_f] → playful and elegant at the same time. I like [name_f]Beatrix[/name_f] [name_f]Daphne[/name_f] and [name_f]Beatrix[/name_f] [name_f]Ivy[/name_f]
[name_f]Zinnia[/name_f] [name_f]June[/name_f] → zippy and bright
[name_f]Aurelia[/name_f] [name_f]Daphne[/name_f] → glowy and golden – I like it!
I think the only ones I’m not so sold on are [name_f]Olive[/name_f], [name_f]Octavia[/name_f] and [name_f]Dahlia[/name_f] as first names as they feel a bit close to O and C’s names?
A few other ideas:
[name_f]Tallulah[/name_f] [name_f]Pearl[/name_f]
[name_f]Amelie[/name_f] [name_f]Winter[/name_f]
[name_f]Ingrid[/name_f] [name_f]Aurelia[/name_f]
[name_f]Evelina[/name_f] [name_f]Juliet[/name_f]
[name_f]Xanthe[/name_f] [name_f]Clementine[/name_f]
[name_f]Anthea[/name_f] [name_f]June[/name_f]
[name_f]Paloma[/name_f] [name_f]Daphne[/name_f]
[name_f]Linnea[/name_f] [name_f]Juliet[/name_f]
[name_f]Anastasia[/name_f] [name_f]Pearl[/name_f]