No info yet
I think these names fit the criteria:
I like Lachlan, Ethan, Ian or Declan for boys, I think the ending plays well with Collin and Rowan and they have the same sort of vibe. (Also, my dad is Ian and he has a brother called Collin. He also has a brother, Paul if that interests you?) I also like Alistair in this sibset.
For girls I like Vivian, Iris, Piper, Hazel, Teagan, and Erin.
Eugene (b), Harold (b), Chester (b), Ida (g), Clarice (g), Florence (g), Hugh (b), Winifred (g), Adeline (g), Wallace (b)
and Rupert (b)
Okay, this is just a list of 18 with no special rules and a 9/9 split:
Soren ZevNicholas PhoenixJared BraveApollo ShepherdRubeus DrakeOwen CypressSebastian CorJude RevereWyatt Sage
Ivy LarkJacinta PrudenceDaphne WrenAthena LuxCara BridgetImogen AzuraCordelia WillowHazel ColletteSaskia Cleo
I really had to dig deep there at the end! I'm pretty happy with how it ended up but I'm not sure if all of them work together.