I’ve done some serious reevaluating on my name lists, and I’ve created my dream sibling set. [name_f]Cecily[/name_f] [name_f]Imogen[/name_f], [name_m]Andrew[/name_m] [name_m]Joseph[/name_m], [name_m]Edward[/name_m] [name_m]Joshua[/name_m] and [name_u]Darcy[/name_u] [name_u]James[/name_u]. I need more girls names to add though, and the more names for each gender that I can add, the better (As a child, I wanted 12 children, now I’m looking towards 8). For girls, I’d like something vintage and, either sweet ([name_f]Cecily[/name_f] or [name_f]Alice[/name_f]) or with a sweet nickname ([name_f]Josephine[/name_f], [name_f]Primrose[/name_f], [name_f]Ottoline[/name_f]). With the boys names, anything classic sounding is lovely. As for middle names, I’d like girls to have an I middle name, and boys to have a J one. 
Your names flow so nicely together, hopefully some of my suggestions can help!
Girls:
[name_f]Elodie[/name_f] [name_f]Isadora[/name_f]
[name_f]Anneliese[/name_f] [name_f]Ivy[/name_f]
[name_f]Primrose[/name_f] [name_f]Iliana[/name_f]
[name_f]Helena[/name_f] [name_f]Ingrid[/name_f]
[name_f]Josephine[/name_f] [name_f]Iris[/name_f]
[name_f]Matilda[/name_f] [name_f]Irissa[/name_f]
[name_f]Fleur[/name_f] [name_f]Isabelle[/name_f] or [name_f]Fleur[/name_f] [name_f]Isobelle[/name_f]
Boys:
[name_m]Christopher[/name_m] [name_u]Jaden[/name_u]
[name_m]Henry[/name_m] [name_m]Josiah[/name_m]
[name_m]Rupert[/name_m] [name_m]Jonah[/name_m]
[name_m]Stephen[/name_m] [name_m]Jeremiah[/name_m]
[name_u]Morgan[/name_u] [name_u]Jude[/name_u]
Giving up my long thought of sib set list:
[name_f]Tesla[/name_f] [name_u]Flynn[/name_u]
[name_u]Zephyr[/name_u] [name_m]Hayes[/name_m]
[name_m]Beckett[/name_m] [name_m]John[/name_m]
[name_u]Emerson[/name_u] [name_u]James[/name_u]
[name_f]Alouette[/name_f] [name_f]Alice[/name_f]
I love [name_f]Primrose[/name_f] & [name_f]Josephine[/name_f], and I’d use [name_f]Posey[/name_f] as a nn for both, but I think I prefer [name_f]Josephine[/name_f] [name_f]Iris[/name_f] slightly more! For boys, [name_m]Henry[/name_m] [name_m]Josiah[/name_m] & [name_u]Morgan[/name_u] are lovely!