Oh, I love your big kids’ names so much! Those combos of a classic first with an unexpected, whimsical middle just feel so perfect.
I will say, [name_m]Giovanni[/name_m] feels like a pretty different vibe to me compared to [name_m]Henry[/name_m] and [name_f]Margot[/name_f], and [name_m]Ulysses[/name_m] feels quite different from [name_u]Atlas[/name_u] and [name_u]Story[/name_u]. I’d call [name_m]Giovanni[/name_m] long, romantic, and very Italian–whereas [name_m]Henry[/name_m] and [name_f]Margot[/name_f] feel short-and-sweet, a little bit vintage, and, well, not specifically Italian. Then [name_m]Ulysses[/name_m] feels like an offbeat old-fashioned pick whereas [name_u]Atlas[/name_u] and [name_u]Story[/name_u] are more whimsical-word-name-y. Not that sibling names have to match by any means, of course! [name_m]Just[/name_m] something I’m noticing, especially because [name_m]Henry[/name_m] and [name_f]Margot[/name_f] do kind of match (at least in my eyes).
On the other hand, [name_m]Henry[/name_m], [name_f]Margot[/name_f], and [name_m]Giovanni[/name_m] do all have a little bit of European flair that ties them together. And they’re all old, classic names with history. The more I see the three of them together, the more I can start to see them as a sibling set. Also, to me they sound better-matched spoken aloud than written together, which I think bodes well. And I do really like the idea of [name_u]Gio[/name_u] as a nickname for [name_m]Giovanni[/name_m]. So while it might not feel like the absolute most natural combo to me personally, I can see it working–especially if [name_m]Giovanni[/name_m] is meaningful to you.
As far as middles, I think [name_f]October[/name_f] itself could be kind of awesome with [name_u]Atlas[/name_u] and [name_u]Story[/name_u]! [name_m]Giovanni[/name_m] [name_f]October[/name_f] does feel like a lot of name, though. Nameberry’s list of autumn baby names has some cool suggestions: https://nameberry.com/list/351/Names-for-[name_f]Autumn[/name_f]-Babies. [name_m]Forrest[/name_m], [name_u]Poe[/name_u], [name_u]Cedar[/name_u], [name_m]Crispin[/name_m], [name_u]Pine[/name_u]? Outside of fall-themed names, I think I’d be inclined to pair [name_u]Atlas[/name_u] and [name_u]Story[/name_u] with something like [name_u]Orion[/name_u], [name_u]Lux[/name_u], [name_u]Fable[/name_u], [name_u]Echo[/name_u], [name_u]True[/name_u], [name_u]Ever[/name_u], [name_u]Prairie[/name_u], [name_u]River[/name_u], [name_u]Brave[/name_u], [name_u]Bright[/name_u], [name_u]Cove[/name_u], etc.