The late Alice Pearce who played Gladys Kravitz in the black and white episodes (she did an outstanding job,too)died,and the producers had to recast the role,who chose Sandra Gould(who,try though she might,was NOT as good as Alice Pearce was)to be Gladys?Was it the decision of ABC?The producers?Or Elizabeth Montgomery herself?

Back in those days, people just didn't write real-life deaths into TV shows, especially sitcoms. To recast was the norm - or to just write a character out of town and bring in their cousin or something. (See also Green Acres, Dennis the Menace, Petticoat Junction, etc.)