Why does annemarie think that great aunt birte does not exist? do you think her suspicion is correct? why or why not?

Annemarie's suspicions are first raised when she hears her uncle and mother engaging in unusual conversations. Shortly after, Mama tells Annemarie that there will be a funeral that night for her great-aunt Birte. Annemarie is further confused because she knows that she does not have a great-aunt named Birte, and in addition, no one seems sad that a 'relative' has died.