Final answer:
Annemarie thinks that Great Aunt Birte does not exist because she has never seen or heard about her, but her suspicion is not correct.
Step-by-step explanation:
Annemarie thinks that Great Aunt Birte does not exist because she has never seen or heard about her. She believes that her parents made up the story of Great Aunt Birte to protect her from the truth about the war and the dangers it poses. Annemarie's suspicion is not correct because it is later revealed that Great Aunt Birte does exist, but she is in fact dead.