It's not important to me that
Linnea and Levin both start with an "L" because the names are not too similar. But again: I really prefer Linnéa. It also looks more interesting and isn't invented like other names with accents.
I like
Noah but prefer it when pronounced English.
I think Levin is OK but I find it a bit boring and not really apt for an adult. It sounds way too soft and meaningless, in my opinion.
Siblings could be named:
Linnea, Levin,
Noah and...
Finja
Sünje
IdaOliviaAnnikaMarjaMarianneWandaWanja
FinnAntonEmilTjorben /
ThorbenJonte
JaronKjellBennet
Sören
PhillipJannis
Ruven
Anything you like?