Barbara Baxley played Natasha in the Broadway Three Sisters. Winters only did the film.
Stanley walked off the production mid-run and was replaced by Page, who in turn was replaced as Olga by Feury. Stanley and Kevin McCarthy despised each other, which was a big factor in her decision to abruptly quit after two months.
When the production played London a year later, George C. Scott replaced McCarthy as Vershinin. But both Stanley and McCarthy returned for the movie, at Strasberg's request.
You probably know this, but Stanley never acted again on stage after the New York and London productions of Three Sisters.