Okay so here are my thoughts… I think to make your sibset with [name_m]Declan[/name_m] and [name_f]Eleanor[/name_f] “work” you should probably stick to classic names. But to satisfy your craving for the more unusual, you could either pick a very underused, under the radar vintage name or use a more modern name ([name_u]Finley[/name_u], [name_u]Quinn[/name_u], etc.) as a middle name. I, personally, lean towards sticking with a classic first and a modern middle because even [name_f]Claire[/name_f], [name_f]Greer[/name_f] and [name_f]Mary[/name_f], although sounding fresh, have a lot of history to them and have been around for a long time.
Thoughts on your list:
[name_f]Samantha[/name_f]- I like this name well enough, but it sounds very 21st century classic as opposed to a more vintage classic name.
[name_f]Louise[/name_f] ([name_f]Lulu[/name_f]) - This would work great.
[name_f]Elizabeth[/name_f] ([name_f]Libby[/name_f])- If you’re concerned about two “el” names, I would take this one off the list. [name_m]Even[/name_m] though it’s very pretty, I think you have other, more interesting choice to look in to.
[name_f]Margaret[/name_f]- This also works great. It has a very similar feel to [name_f]Eleanor[/name_f] for me. Although my favorite nickname for [name_f]Margaret[/name_f] is [name_f]Maisie[/name_f].
[name_f]Georgia[/name_f] ([name_f]Gigi[/name_f])- This is pretty and vintage but for the nickname [name_f]Gigi[/name_f], I’ve always preferred the full name [name_f]Evangeline[/name_f] or [name_f]Genevieve[/name_f].
[name_u]Evelyn[/name_u] ([name_f]Evie[/name_f])- It’s such a pretty name, I understand why you’ve gravitated towards it! It was on my list at one point too but I had the same concern. Other alternates I explored that are similar but not as popular: [name_f]Eveline[/name_f], [name_f]Eve[/name_f].
[name_f]Josephine[/name_f] ([name_u]Josie[/name_u])- This would also work wonderfully.
[name_f]Brianna[/name_f] ([name_f]Bree[/name_f])- This is great for a middle name, but I don’t know if it stands up to the boldness of [name_m]Declan[/name_m] and [name_f]Eleanor[/name_f] which have stronger sounds in them.
[name_f]Estelle[/name_f] ([name_f]Stella[/name_f]?)- Same as before, if you’re worried about the “el” names, I would get rid of this one.
Here are other classics with nicknames to consider mixing with a more modern middle name like [name_u]Finley[/name_u] or [name_u]Quinn[/name_u] (or may I also add [name_f]Greer[/name_f], [name_f]Kenna[/name_f], [name_u]Eden[/name_u], [name_f]Mara[/name_f] (mah-rah), [name_f]Vera[/name_f], [name_f]Zara[/name_f], [name_f]Noemi[/name_f] or [name_u]Reese[/name_u] would make lovely middles):
[name_f]Adelaide[/name_f] nn [name_f]Ada[/name_f], [name_f]Addie[/name_f], Dela, [name_f]Laidey[/name_f]
[name_f]Annabelle[/name_f] nn [name_f]Anna[/name_f], [name_f]Belle[/name_f], [name_f]Elle[/name_f]
[name_f]Anneliese[/name_f] nn [name_f]Anne[/name_f], [name_f]Annie[/name_f], [name_f]Elise[/name_f], Liesey (lee-see)
[name_f]Evangeline[/name_f] nn [name_f]Eve[/name_f], [name_f]Evie[/name_f], [name_f]Eva[/name_f], [name_f]Vangie[/name_f], [name_u]Angie[/name_u], [name_u]Angel[/name_u], [name_f]Gigi[/name_f], [name_f]Lina[/name_f]
[name_f]Genevieve[/name_f] nn [name_f]Genie[/name_f], [name_f]Eve[/name_f], [name_f]Evie[/name_f], [name_f]Neve[/name_f], [name_f]Vivi[/name_f], [name_f]Gigi[/name_f]
[name_f]Georgiana[/name_f] nn [name_f]Ana[/name_f], [name_f]Gianna[/name_f]
[name_f]Guinevere[/name_f] nn [name_f]Gwen[/name_f], [name_f]Vera[/name_f], [name_f]Winnie[/name_f]
[name_f]Gwyneth[/name_f] or [name_f]Gwendolyn[/name_f] nn [name_f]Gwen[/name_f], [name_f]Winnie[/name_f]
[name_f]Magnolia[/name_f] nn [name_f]Maggie[/name_f], [name_u]Noli[/name_u], [name_f]Nola[/name_f], [name_f]Lia[/name_f]
[name_f]Phillipa[/name_f] nn [name_f]Pippa[/name_f]
[name_f]Rosalie[/name_f] nn [name_f]Rose[/name_f], [name_f]Rosie[/name_f], [name_u]Leigh[/name_u]
[name_f]Rosaline[/name_f] nn [name_f]Rose[/name_f], [name_f]Rosie[/name_f], [name_f]Lina[/name_f] (leena)
Here are some truly vintage names that are way off the radar if that idea appeals to you:
[name_f]Araminta[/name_f] nn [name_f]Minnie[/name_f]
[name_f]Amaryllis[/name_f] nn [name_f]Amy[/name_f], [name_f]Lissie[/name_f]
[name_f]Aurelia[/name_f] nn [name_f]Lia[/name_f], [name_f]Ria[/name_f]
[name_f]Camellia[/name_f] nn [name_f]Cammie[/name_f], [name_f]Mila[/name_f], [name_f]Millie[/name_f], [name_f]Lia[/name_f]
[name_f]Lavinia[/name_f] (like [name_f]Eleanor[/name_f], I prefer this one without a nickname)
[name_f]Seraphina[/name_f] nn [name_f]Sera[/name_f]
[name_f]Theodosia[/name_f] nn [name_f]Thea[/name_f], [name_f]Tea[/name_f], [name_f]Theda[/name_f]
[name_f]Verity[/name_f]
My favorites from your list would be:
[name_f]Louise[/name_f] [name_f]Noemi[/name_f] or [name_f]Louise[/name_f] [name_u]Finley[/name_u]
[name_f]Margaret[/name_f] [name_u]Reese[/name_u] or [name_f]Margaret[/name_f] [name_u]Quinn[/name_u]
[name_f]Josephine[/name_f] [name_f]Mara[/name_f] or [name_f]Josephine[/name_f] [name_f]Kenna[/name_f]
My favorites from my list would be:
[name_f]Aurelia[/name_f] [name_f]Greer[/name_f]
[name_f]Genevieve[/name_f] [name_u]Eden[/name_u]
[name_f]Lavinia[/name_f] [name_f]Rose[/name_f]