From your list, I think [name]Garrett[/name], [name]Landon[/name], [name]Savannah[/name], [name]Jocelyn[/name], and [name]Ashlyn[/name] could all work nicely. Although [name]Savannah[/name] is a lot more feminine than [name]Kamryn[/name], so it’s a little iffy, but since she’s old enough, you could maybe bounce it off her and see if she likes it (totally your call on whether to do that or not). [name]Samuel[/name] also kind of works but is fairly different. Here are some other directions:
Boys:
[name]Mason[/name], [name]Kamryn[/name], and [name]Micah[/name] (Biblical like [name]Samuel[/name] but trendier)
[name]Mason[/name], [name]Kamryn[/name], and [name]Benjamin[/name] (Biblical like [name]Samuel[/name] but the -n ending ties it in well)
[name]Mason[/name], [name]Kamryn[/name], and [name]Miles[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Myles[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Emmett[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Tanner[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Barrett[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Xander[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Zander[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Xavier[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Maddox[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Graham[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Grant[/name]
Girls:
[name]Mason[/name], [name]Kamryn[/name], and [name]Makayla[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Emilie[/name] (I would go with two unconventional spellings, weirdly, [name]Emily[/name] is just too much classic)
[name]Mason[/name], [name]Kamryn[/name], and [name]Mia[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Maya[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Aimee[/name] (similar reasoning to [name]Emilie[/name])
[name]Mason[/name], [name]Kamryn[/name], and [name]Sage[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Page[/name]/[name]Paige[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Jordan[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Hadley[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Amber[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Layla[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Sadie[/name]
[name]Mason[/name], [name]Kamryn[/name], and [name]Mila[/name]
Good luck!