My strongest association — St. Kilda, an archipelago, then kelpie, windy weather, fairytales, deep water...
Kelda Imogen &
Kelda Elowen - I like how
Imogen and
Elowen compliment
Kelda: all these names share same vibe, imo.
Kelda Blanche - like how
Blanche softens "square"
Kelda.
It's hard to make a combo for some reason. The first thing that comes to mind is something like -
Kelda Iona - unfortunately it sounds like a tourist route, sights you want to visit.
So, maybe
Kelda Gabrielle Kelda Eiril
Kelda MorvenKelda Nimue Kelda Vivian