What is a sibling boy name for Declan?

Our son is [name]Declan[/name] and we are searching for another boy name. We like [name]Jack[/name] but worry that it is too common especially when put up against [name]Declan[/name]. Our last name is very English.
We generally like strong, somewhat unusual names that are easy for people to understand how to spell properly. (ie: [name]Cian[/name] isn’t pronounced like it’s spelled in the US)

I think [name]Jack[/name] goes very nicely with [name]Declan[/name]…some others that popped into my head were:

[name]William[/name]
[name]Oliver[/name]
[name]Liam[/name]
[name]Owen[/name]
[name]Quinn[/name]
[name]Finn[/name]

…when worrying about a name that’s too popular, there is a part in the book The [name]Baby[/name] Name [name]Wizard[/name] that I always find helpful. It talks about how there are naming “neighbourhoods”, and a “popular” name like [name]Olivia[/name] may be seldom-heard in a certain area of town/state, etc. but one you think is “rare” like [name]Pearl[/name] is everywhere because parents think it’s rare/trendy etc. So to determine if “[name]Jack[/name]” is really too popular, you should do an informal survey of baby groups, preschool classes, friends you know having babies, people who know people having babies, etc. to see if it really is popular where you are or not.

FYI— I was at a playgroup yesterday and there were TWO each of: [name]Ruby[/name], [name]Hazel[/name], [name]Harper[/name] and [name]Flora[/name]…all names that I would have thought were super-rare, but are very trendy in my neighbourhood!!!

[name]Declan[/name] and [name]Hudson[/name]
[name]Declan[/name] and [name]Samson[/name]
[name]Declan[/name] and [name]Jericho[/name]
[name]Declan[/name] and [name]Winston[/name]
[name]Declan[/name] and [name]Jarrett[/name]
[name]Declan[/name] and [name]Cooper[/name]
[name]Declan[/name] and [name]Tristan[/name]
[name]Declan[/name] and [name]Garrison[/name]
[name]Declan[/name] and [name]Evander[/name]
[name]Declan[/name] and [name]Porter[/name]
[name]Declan[/name] and [name]Finnian[/name]
[name]Declan[/name] and [name]Nolan[/name]
[name]Declan[/name] and [name]Granger[/name]
[name]Declan[/name] and [name]Leander[/name]
[name]Declan[/name] and [name]Holden[/name]
[name]Declan[/name] and [name]Talon[/name]
[name]Declan[/name] and [name]Bennett[/name]
[name]Declan[/name] and [name]Gordon[/name]
[name]Declan[/name] and [name]Micah[/name]
[name]Declan[/name] and [name]Tatum[/name]
[name]Declan[/name] and [name]Rafferty[/name]
[name]Declan[/name] and [name]Cassius[/name]
[name]Declan[/name] and [name]Easton[/name]
[name]Declan[/name] and [name]Ramsey[/name]
[name]Declan[/name] and [name]Asher[/name]
[name]Declan[/name] and [name]Marcus[/name]
[name]Declan[/name] and [name]Everett[/name]
[name]Declan[/name] and [name]Orion[/name]

[name]Declan[/name] & [name]Connolly[/name]
[name]Declan[/name] & [name]Cormac[/name]
[name]Declan[/name] & [name]Fergus[/name]
[name]Declan[/name] & [name]Garrett[/name]
[name]Declan[/name] & [name]Ivor[/name]
[name]Declan[/name] & [name]Macaulay[/name]
[name]Declan[/name] & [name]Magnus[/name]
[name]Declan[/name] & [name]Rhys[/name]
[name]Declan[/name] & [name]Rhodri[/name]
[name]Declan[/name] & [name]Seamus[/name]
[name]Declan[/name] & [name]Tierney[/name]
[name]Declan[/name] & [name]Vaughan[/name]
[name]Declan[/name] & [name]Alastair[/name]
[name]Declan[/name] & [name]Heath[/name]
[name]Declan[/name] & [name]Barnaby[/name]
[name]Declan[/name] & [name]Callum[/name]
[name]Declan[/name] & [name]Byron[/name]
[name]Declan[/name] & [name]Justin[/name]
[name]Declan[/name] & [name]Atticus[/name]
[name]Declan[/name] & [name]Jasper[/name]
[name]Declan[/name] & [name]Lucius[/name]
[name]Declan[/name] & [name]Gulliver[/name]
[name]Declan[/name] & [name]Conrad[/name]
[name]Declan[/name] & [name]Merritt[/name]
[name]Declan[/name] & [name]Cyrus[/name]
[name]Declan[/name] & [name]Sawyer[/name]
[name]Declan[/name] & [name]Thane[/name]
[name]Declan[/name] & [name]Cooper[/name]
[name]Declan[/name] & [name]Rowland[/name]
[name]Declan[/name] & [name]Ramsey[/name]
[name]Declan[/name] & [name]Maxwell[/name]
[name]Declan[/name] & [name]Hayes[/name]

I know a [name]Declan[/name] whose brothers are [name]Patrick[/name] and [name]Brendan[/name]. You could go with an Irish theme without choosing names that no one can pronounce.

Irish Boy Names
[name]Brady[/name]
[name]Brennan[/name]
[name]Casey[/name]
[name]Connor[/name]/[name]Conor[/name]
[name]Finn[/name]
[name]Grady[/name]
[name]Keenan[/name]
[name]Keiran[/name]
[name]Liam[/name]
[name]Murphy[/name]
[name]Neal[/name]/[name]Neil[/name]
[name]Quinn[/name]
[name]Riley[/name]
[name]Rory[/name]
[name]Seamus[/name]
[name]Shay[/name]
[name]Sullivan[/name]

I do like [name]Jack[/name] and [name]Declan[/name] a lot though. I think that could be a great sibling set even if they are different styles or one is common and the other is uncommon. Good luck!

We have a little [name]Declan[/name]! I love [name]Kieran[/name] as a brother name.

My faves
[name]Declan[/name] and [name]Liam[/name]
[name]Declan[/name] and [name]Rory[/name]
[name]Declan[/name] and [name]Quinn[/name]

I love:

[name]Declan[/name] & [name]Beckett[/name]
[name]Declan[/name] & [name]Finnegan[/name]
[name]Declan[/name] & [name]Jack[/name]
[name]Declan[/name] & [name]Rhys[/name] (pronounced [name]Reece[/name])
[name]Declan[/name] & [name]Rufus[/name]
[name]Declan[/name] & [name]Graham[/name]
[name]Declan[/name] & [name]Jude[/name]
[name]Declan[/name] & [name]Cormac[/name]
[name]Declan[/name] & [name]Grady[/name]
[name]Declan[/name] & [name]Freddie[/name]
[name]Declan[/name] & [name]Henry[/name]
[name]Declan[/name] & [name]Charlie[/name]
[name]Declan[/name] & [name]Oliver[/name]