Zeke’s nicely unusual
It’s a proper name though, so I’d avoid anything made up for a sibling. Rafe is great, Rafferty is OK, don’t like the rest.
Blaise, Saul, Levi, Elijah nn Eli, Caleb, Guy, Lorne, Kester, Ivor, Gawain, Ezra, Seth, Joss, Jerome, Jethro,
For girls I don’t like Kaia (and I’d just assume you were calling her after the model), but Laken is really odd (sorry!)
Astra, Aster, Aphra, Catrin, Lois, Linos, Ines, Ffion, Jocelyn, Stella, Zelda, Hera, Aislinn (Ash-lin), Arran, Manon