To be honest, that poor child has had so much turmoil, they need to leave her name Sydney, no matter who named her. There has been so much upheaval and a little consistency would be good for this baby.
Did I read that Sydney was an old family name from either the Hortons or Graysons. I seem to remember it being mentioned on the message boards when Nicole first named her. Could be wrong. I agree that the name should remain the same; she has been through enouh changes already.