You should pick a name for your child because you love it. If you love more K names, then more power to you, use a K name! If not, I don’t think it’s the end of the world to stray from the theme, especially if you end up having two or more children who will not have K names. I think it’s more important that you be able to tell your child you picked a name you loved rather than a name you only thought was okay but fit the theme. That being said, I think there are a bunch of great K names you could use to fit with [name]Kadence[/name] and [name]Kellen[/name]:
Girls: [name]Karsten[/name], [name]Keira[/name], [name]Kaia[/name]/[name]Kaya[/name], [name]Kendall[/name], [name]Kimberley[/name], [name]Kimball[/name], [name]Karina[/name], [name]Katrina[/name], [name]Kara[/name], [name]Keturah[/name], [name]Kalilah[/name], [name]Kallista[/name], [name]Kensington[/name], [name]Kendra[/name], [name]Katya[/name], [name]Kismet[/name], [name]Kennedy[/name].
Boys: Kramer, [name]Kai[/name], [name]Kirby[/name], [name]Knox[/name], [name]Keegan[/name], [name]Kane[/name], [name]Keanu[/name], [name]Keaton[/name], [name]Keifer[/name], [name]Kieran[/name], [name]Kent[/name], [name]Keane[/name], [name]Kingsley[/name], Kipton, Kipling.
I think [name]Kadence[/name], [name]Kellen[/name], [name]Keira[/name] and [name]Kirby[/name] would make an awesome set.