Twist of Fate or Twist N Shout are both great registered names and seem to fit with what the breeder wants for registered names. Along the same lines would be Karma or Fluke.
Also Chimère meaning: dream, wild dream, a wild or unrealistic notion, pipedream, fantastic idea seems to fit pretty well.
Of course I think Whimsy/Whim is an awesome name. Especially with the registered name Whimsical