Isadore Weisfelt, the father of Arthur Nielsen, was portrayed by Judd Hirsch. A renowned professor of music, Isadore and Artie haven't spoken in decades due to an estrangement because of Isadore's belief that Artie had abandoned and forsaken music. Artie led everybody who knew him before to believe that he (Artie) had died, primarily for their own safety. Claudia Donovan, while attempting find Artie's childhood piano in Secret Santa, uncovered the fact that Isadore was very much alive. She lured Isadore to Leena's and, with Joshua's aid, she effected a reconciliation. Indeed, in their mutual griping at her high-handedness and inability to keep her nose out of other people's business, Claudia was spiritually as well as physically responsible for their getting back together.