Why was Kristi sent to bed before Aunt Birtes funeral

Mama claims to have a aunt who passes away in Chapter 8. However, Great-Aunt Birte does not really exist. Mama and Uncle Henrik make her up so that they can hold a funeral, which is really an excuse for Uncle Henrik to collect all the Jewish refugees at his home before smuggling them to Sweden. This meeting was very late and a little dangerous so Kristi was sent to bed.