Sorry to post yet again ... I've been ill today, so online more than usual ...
Dashiell is a family name I've found - my great-grandmother's maiden name. (I've researched a lot about her and she led an amazing life.)
Bearing this in mind, WDYTO Dashiell for a girl? While a lot of surnames sound masculine, this doesn't at all (to me).
Maybe Dashiell Natalia?