Are these too similar to use as siblings? There would be other siblings first if I ever used both, like [name_f]Willa[/name_f] and [name_f]Olive[/name_f]. They don’t sound similar but they do look similar.
I think they pair well as sibling names!
First off I love [name_f]Willa[/name_f] and [name_f]Olive[/name_f] together! [name_u]Eden[/name_u] is my least favorite of the group and I think it’s a little close to [name_f]Esme[/name_f] but with the other names I don’t think it’s such a big deal. [name_u]Love[/name_u] [name_f]Willa[/name_f], [name_f]Olive[/name_f] and [name_f]Esme[/name_f] together. [name_f]Esme[/name_f] was one of my top choices for both of my pregnancies but my husband staunchly vetoed it both times. 
I think they work fine -they sound good together but also different 
I adore [name_u]Eden[/name_u], but I think [name_f]Willa[/name_f], [name_f]Olive[/name_f], and [name_f]Esme[/name_f] are perfection together! I run into this same problem with repeating initials in my sibsets as well, because I love multiple names that start with C, F, A, M, and O. I think in this case they work because they have such different sounds.
I wouldn’t use them alone, but if they are split up by other names, I think they are fine together. However, like others have said, I’d probably use [name_f]Esme[/name_f] first because I think it goes so well with [name_f]Willa[/name_f] and [name_f]Olive[/name_f].