[name_m]Miles[/name_m]! It’s a great name, fits the vibe of [name_m]Sonny[/name_m] and [name_f]Ayla[/name_f], but it’s still distinct from them. (Ollie and [name_m]Ellis[/name_m] are a bit close in sound to [name_f]Ayla[/name_f], [name_m]Spencer[/name_m] shares that first initial with [name_m]Sonny[/name_m], but [name_m]Miles[/name_m] really has its own identity.)
I think Miles is perfect! I agree with @LoloTen that id avoid having shared initials (e.g. Sonny and Spencer) and Ollie and Ellis are a bit too similar to Ayla. Oakley is good too but maybe a bit of a different vibe to your other kids. Finn would also work great though!
Some more ideas if you want just in case that doesn't feel right:
Archie - “genuine, bold”
Ben / Benny - “son of the right hand”
Bodhi / Beau - “awakening, enlightenment” / “handsome”
Emmett - “truth; universal”
Emrys - “immortal”
Evan - “God is gracious”
Ezra - “help, helper”
Felix - “happy, fortunate”
Fletcher - “arrow maker”
Flynn - “son of the red-haired one”
Frankie - “free one”
Hugo - “mind, intellect”
Jasper - “treasurer; bringer of treasure”
Joel - “Yahweh is God”
Jude - “praise”
Leo - “lion”
Levi - “joined, attached”
Luca - “bringer of light”
Louie / Louis - “famous warrior”
Max - “greatest”
Micah - “who is like God?”
Milo - “merciful”
Noah - “rest, comfort”
Noel - “birth; Christmas”
Otis - “wealth, fortune”
Otto - “wealth, prosperity”
Owen - “young warrior; well-born”
Robin - “bright fame” (also a bird)
Rory - “red king”
Ryan - “little king”
Rowan - “little red one” (also a tree)
Teddy / Theo - “gift of God”
[name_m]Miles[/name_m] also gets my vote! It’s got a distinct sound but similar vibes. Being modern in sound and usage as well as having a long history and a vintage side, [name_m]Miles[/name_m] also bridges both [name_m]Sonny[/name_m] and [name_f]Ayla[/name_f] really well. I do also like [name_m]Oakley[/name_m] for you (I like how all names would share a Y) but [name_m]Miles[/name_m] is the slightly better fit for me.
I would go with [name_m]Miles[/name_m] as it has the same friendly, breezy vibe as [name_m]Sonny[/name_m] and [name_f]Ayla[/name_f] and adds some new sounds to the mix. [name_f]My[/name_f] runner-up would be [name_m]Ollie[/name_m] which feels exactly like a brother name to [name_m]Sonny[/name_m] (gives me surfer vibes) but it shares similar sounds with both [name_m]Sonny[/name_m] and [name_f]Ayla[/name_f] which puts it in second place.
[name_f][/name_f]
[name_m]Ellis[/name_m] and [name_m]Spencer[/name_m] feel preppy to me so not my first choice. I think [name_m]Oakley[/name_m] works but it makes the sibling set feel a very on-trend and loses that breezy vibe for me.
I would go (in order) Miles, Ellis, Ollie, or Finn - as gentle, causal and relaxed but also trim & tailored, like your other two.
I don’t like the repeat S in Spencer and don’t really see it matching. Oakley, I agree is a little too trendy/ stylised, and pretty intense for what should be a low key, nature name
I really love [name_m]Finn[/name_m] and [name_m]Miles[/name_m] for you! They both fit the vibe of [name_m]Sonny[/name_m] and [name_f]Ayla[/name_f] perfectly!
I’m agreeing with everyone else I think [name_m]Miles[/name_m] is gorgeous such a handsome name that feels cohesive within your sibling set whilst having his own identity. I also in general really love the name [name_m]Miles[/name_m].
Congratulations on baby boy! [name_f][/name_f] [name_m]You[/name_m] have a lot of lovely options. [name_f][/name_f] I think [name_m]Finn[/name_m] is my favorite with your kiddos, followed shortly by [name_m]Miles[/name_m]! [name_f][/name_f] I also am very fond of [name_m]Ellis[/name_m] with [name_m]Sonny[/name_m] and [name_f]Ayla[/name_f].