Point of information, pctechxp & Dave:
The name of Frank Zappa's first son was not originally Dweezil. It was Ian. He later insisted that his parents get his name legally changed to Dweezil.
It is true that Frank & Gail Zappa did originally want to call him Dweezil, but were banned from registering that name by the hospital where he was born.
As for their oldest child - her name is Moon. Unit is her middle name. Do you go around referring to Michael Heseltine as "Michael Dibdin"? Or Gordon Brown as "James Gordon"?