Complex sentence: Estelle, while never referred that way on the show, was said by both Larry David and Jason Alexander to be Jewish, and in numerous interviews they said that George was "half-Jewish," implying that Frank was not.
Split into simpler sentences: Estelle, while never referred to that way on the show, was said by both Larry David and Jason Alexander to be Jewish. They also said in numerous interviews that George was "half-Jewish," implying that Frank was not.