Who is Agnes T. Ritter, Mrs. (Sabra) Ritter from The Persian Pickle Club and what is their importance?

The sharp-tongued Agnes is Rita's sister-in-law, while the much gentler Mrs. Judd is her mother-in-law. Both are members of long standing in the Persian Pickle Club, which is the reason for Rita's membership - they simply assume that she will be interested and/or active in the Club's activities, making no effort to find out whether she actually would be. Agnes, embittered by the way she was treated as a child, is a bitter old woman in a young woman's body (she is revealed to be, like Queenie, in her mid twenties).