@ my name.....
The wtbts was established with certain core beliefs which constituted a ' foundation ' which they widely published thereby recruiting followers who adhered to those beliefs. These beliefs were seen as the true understood word of god. These core ( foundation ) and subsequent beliefs have been rejected by the contemporary governing body. This rejection even if justified as ' new light ' is their own admission of the original foundational teachings/ beliefs having been unsound. Therefore they admit the original foundations of wtbts was unsound every time they announce new light.
Best wishes.