Conversation so far:
when was all about eve developed?
The story of All About Eve originated in an anecdote related to Mary Orr by actress Elisabeth Bergner during 1943 and 1944.
what was the anecdote related to Mary Orr by actress Elisabeth Bergner that originated the story of All About Eve?
While performing in The Two Mrs. Carrolls 1943-1944, Bergner allowed a young fan to become part of her household, regretting her generosity when the woman attempted to undermine her.
why did Bergner regret the generosity she showed the young fan?
In the story, Orr gives the girl a more ruthless character and allows her to succeed in stealing the older actress' career. Bergner later confirmed the basis of the story.

Question: how did she try to undermind her?
Self-contained rewrite: how did the young fan try to undermind Bergner?