The Grandfather paradox involves a time traveler going back into the past and killing his grandfather before he meets his grandmother. This then creates the situation in which the time travel is never actually born and therefore could not travel in time to kill his grandfather.
Effectively this is what the current governing body of Jehovah's Witnesses have actually done. Using historical revisionism as the time machine they have traveled back in time and deleted the existence of the faithful and discreet slave class. This has then created a situation in which the faithful and discreet slave class never existed and therefore could never have appointed a representative governing body.