What do Du think of this set of sibling names?

Nice. They sound very seasonal, I like them. I can already imagie how they look.

They sound very pretty :)

Very beautiful names. But maybe instead of making their first and middle names correspond so heavily (Winter and December, Aurora and Dawn), Du could make their names opposites... so have one of their first names be about summer and middle name about sunset. Or, Du could give them opposite first names but the same/similar middle name, signifying both the differences and underlying similarities between the twins. Just a thought.