I like names like ; : [name_m]Graham[/name_m], [name_u]Everett[/name_u], [name_u]Owen[/name_u], [name_m]Malcolm[/name_m], [name_u]Emmett[/name_u]
His taste is more. [name_u]William[/name_u], [name_m]Theodore[/name_m], [name_u]Benjamin[/name_u], [name_m]Andrew[/name_m]
Sounds like [name_m]Theodore[/name_m] nn [name_u]Theo[/name_u] might be a good compromise. Other than that [name_m]Grant[/name_m] would get my vote.
I second the suggestion of [name_m]Graham[/name_m]! [name_u]Henry[/name_u], [name_u]Evan[/name_u], [name_f]Daphne[/name_f] and [name_m]Graham[/name_m] feel like a nice cohesive set.
I was also going to suggest [name_m]Nicholas[/name_m]. It gives me the same feel as your other names. Also the nn’s [name_m]Cole[/name_m], [name_m]Claus[/name_m], [name_u]Nico[/name_u] and [name_u]Nick[/name_u] are fun options.
[name_m]Abram[/name_m]
[name_u]Alden[/name_u]
[name_m]Alexander[/name_m] nn [name_u]Alex[/name_u], [name_u]Lex[/name_u], [name_m]Xander[/name_m]
[name_u]Beau[/name_u]
[name_u]Bowen[/name_u]
[name_u]Brooks[/name_u]
[name_u]Cooper[/name_u]
[name_u]Calder[/name_u]
[name_m]Collin[/name_m]
[name_m]Simon[/name_m]
[name_m]Eldon[/name_m]
[name_u]Elliott[/name_u]
[name_u]Ellis[/name_u]
[name_m]Felix[/name_m]
[name_m]Ford[/name_m]
[name_u]Hale[/name_u]
[name_u]Hayden[/name_u]
[name_m]Heath[/name_m]
[name_m]Ian[/name_m]
[name_u]Ira[/name_u]
[name_u]James[/name_u]
[name_u]Julian[/name_u]
[name_u]Levi[/name_u]
[name_u]Logan[/name_u]
Louis/Lewis
[name_m]Roman[/name_m]
[name_m]Samuel[/name_m]
[name_u]Sawyer[/name_u]
[name_u]Shea[/name_u]
[name_m]Taft[/name_m]
[name_u]Tate[/name_u]
[name_m]Vincent[/name_m]
[name_u]West[/name_u]
[name_u]Wesley[/name_u]
[name_u]Wyatt[/name_u]
[name_u]Wynn[/name_u]
[name_m]Grant[/name_m] or [name_m]Theodore[/name_m] work well -or even just [name_u]Theo[/name_u] if [name_m]Theodore[/name_m] feels too long/has nicknames.
[name_m]Nathan[/name_m], Lucas/Luca, [name_u]Leon[/name_u], [name_u]Jasper[/name_u], [name_u]Bennett[/name_u] and [name_m]Reuben[/name_m] are my suggestions
For our second son , Evan we put together the sounds of Everett (my fav) and Owen (his fav). That’s why Evan might feel a bit different than the others but we absolutely love it. Then we had a daughter , and now a surprise 4th ( a boy!). We are considering now using those in a different way as they are still our current favorite boy names for this baby. Considering Owen Everett.
If not then he’s liking Theodore which I like as well. And my choice would be Oliver but a close family member used it already, same with Finn. Next my favs are Arthur, Graham and Malcolm. Any of these seem an on the nose perfect fit?
Now thinking from input about these ideas:
Owen Arthur
Owen Everett
Theo Everett
Theodore Everett
I like [name_u]Jasper[/name_u] and [name_u]Bennett[/name_u]
[name_u]Love[/name_u] [name_u]Owen[/name_u] (Not too similar to Evan) & [name_m]Nathaniel[/name_m] NN [name_u]Theo[/name_u]. [name_u]Love[/name_u] [name_u]Theo[/name_u] so much! 
Xx 
[name_u]Henry[/name_u] [name_u]Evan[/name_u] [name_f]Daphne[/name_f] and
[name_m]Micheal[/name_m]
[name_u]Percy[/name_u]
[name_m]Caspian[/name_m]
[name_u]Finley[/name_u]
[name_m]Louis[/name_m]
Austin/Auden
[name_m]Ernest[/name_m]
[name_m]Peter[/name_m]
[name_m]Samuel[/name_m]
I like [name_u]Owen[/name_u] [name_u]Everett[/name_u] & [name_m]Theodore[/name_m] [name_u]Everett[/name_u] for you.
Other ideas: [name_m]Nathan[/name_m], [name_m]Graham[/name_m], [name_u]Elliott[/name_u]
[name_u]Owen[/name_u] [name_u]Arthur[/name_u] and [name_u]Theo[/name_u] [name_u]Everett[/name_u] are lovely. I think those sound great for you, and the fit the sibset! [name_u]Owen[/name_u] does feel quite a bit similar to [name_u]Evan[/name_u] for me, personally.
[name_u]Henry[/name_u], [name_u]Evan[/name_u], [name_f]Daphne[/name_f], and…
[name_u]Theo[/name_u] (this fits beautifully in your set!)
[name_u]Quincey[/name_u]
[name_m]Nate[/name_m]
[name_u]Maxwell[/name_u] or [name_u]Max[/name_u]
[name_u]Cohen[/name_u]
[name_u]Jude[/name_u]
[name_u]Neal[/name_u]
[name_u]Elliott[/name_u]
[name_u]Griffin[/name_u]
[name_m]Ronan[/name_m]
[name_m]Peter[/name_m]
[name_m]Herschel[/name_m]
[name_m]Lewis[/name_m]
[name_m]Kellen[/name_m]
[name_m]Luke[/name_m]
[name_m]Gideon[/name_m]
[name_u]Beau[/name_u]
[name_u]Benjamin[/name_u]
[name_u]Holden[/name_u]
[name_m]Fletcher[/name_m]
You might like [name_m]Nathan[/name_m], [name_m]Oscar[/name_m], or [name_m]Graham[/name_m]?
[name_u]Read[/name_u] your other post re: [name_u]Owen[/name_u] and [name_u]Everett[/name_u]. I adore [name_u]Everett[/name_u] but agree that he may not be the best fit. After seeing your list here, I’d like to suggest [name_m]Nathan[/name_m]. I think it’s a little more direct than [name_m]Nathaniel[/name_m] and shares the -n ending with [name_u]Evan[/name_u]. I like that you’d have 2 -ee endings and 2 -an endings in this set.
[name_u]Henry[/name_u], [name_u]Evan[/name_u], [name_f]Daphne[/name_f] & [name_m]Nathan[/name_m]!
And, I think you could definitely do [name_m]Nathan[/name_m] [name_u]Everett[/name_u] if you wanted 