Perseverance counts By ROBERT WAHLS COPELAND is playwright Arthur Miller's baby sister, which in no way explains the unanimous raves she's getting as Vera in "Pal Joey" at Circle In the Square. Big brother warned her against becoming an actress and, after due consultation with her husband Joan became one. The odd theme in Joan's various careers on stage, film and the TV soaps, is that she is constantly being rediscovered. Years back she was standby to Vivien Leigh in the musicalized "Tovarich." Vivien had a nervous breakdown. "Vivien called me one matinee and said I would be going on for her that evening. Her doctors Insisted she rest. She was a husky soprano. So I went on and adapted to her range. I played the rest of the run." Then there was the year standing by for Katharine Hepburn in "Coco." "I met Kate and she told me frankly I would never go on. She told the producer I was a waste of money. And she was right. Every night I waited for the phone call like a house doctor. It never came." After she won a starring role in last season's "Dr. Jazz" with Bobby Van, Joan decided never again to stand by. She sang and she carried the tedious book through months of previews. She would at long last open in a starring role. "Not at all. They gradually cut out all my songs and I quit before the opening. On opening night the cast sent me telegrams, wondering how I knew enough to escape the disaster." Her head a mass of bronze-blonde curls, and wearing an open cotton blouse, Joan took a sip of straight quinine water and went on: "I've been JOAN COPELAND: Standing by no longer. married forever to George Kupchick who's now a professor of environmental sciences at Hunter. And our son, Eric, 24, works for CBS. George has always been supportive, never felt threatened by my career." There were three Miller children growing up In Brooklyn, Kermit, Arthur and Joan. Joan says she was spoiled. She wanted piano lessons but Arthur was given them. "Arthur was more fascinated by touch football. When the piano teacher arrived at the house he was well beyond the rarge of mother's call. So I got to take the piano lessons. We couldn't afford to waste that $3 a week. "I decided to become a concert pianist. But one day, playing a Beethoven sonata, I really listened to myself. I knew I was good but I'd never be great." It wasn't until Joan found herself as George's Army wife at a Texas base that she thought of acting as a career. "They needed some female bodies to cross a stage and deliver one-liners. Something clicked in me." When she got back to Manhattan Joan enrolled In the American Academy of Dramatic Arts. Then she became a charter member of Actors Studio, where later her sister-in-law, Marilyn Monroe, enrolled with Lee Strasberg. "I liked Marilyn very much, but of course I never had to live with her problems. When she felt able to be seen she was delightful, marvelous, particularly with children. Eric was 8 when she arrived at a hospital with a chauffeur carrying a color TV. "None of the kids in the ward knew who she was. And Marilyn loved that. She was warm and unafraid. Of course, the doctors and nurses lined up for a look." The only time Joan worked in an Arthur Miller play, she auditioned for "The Price." Kate Reid got the part, but Joan was the standby and took over when Kate departed. "I asked for it and I got it. I've had roles in the soaps, 'Love of Life,' Search for Tomorrow.' Her reviews as Vera in "Joey" are the best of Joan's varied career, and her "Bewitched, Bothered and Bewildered" is a total hit. She was Noah's wife with Danny Kaye in "Two By Two" and played opposite him when he fractured a leg and worked in a wheel chair. Joan is adaptable. "I wanted to play Vera and I auditioned. Ted Mann liked me. Then I got the call, they'd signed Eleanor Parker. Would I stand by? I almost said no, but I hate being unemployed. And every project is a stretching experience. I said yes.' And so, when Edward Villella and Eleanor Parker, bowed out of "Joey," Joan saved the show and turned it into a personal triumph. "I hope I've had my last job as stand by," she comments. sviviua