When did Annemarie and Ellen have to hide from the German soldiers in Number the Stars?

In Lois Lowry's 1989 novel Number the Stars, the family of ten-year-old Annemarie takes in her Jewish friend Ellen during the Nazi occupation of Denmark. The family pretends that Ellen is Annemarie's deceased sister Lise, trying to protect her from being sent to a concentration camp.
There is an instance in the novel in which Ellen is almost taken by the soldiers after they enter Annemarie's house without warning. Thankfully, Annemarie removes Ellen's necklace, which features the Star of David, before the soldiers are able to see her. The soldiers still almost take Ellen away when they suspect her of being unrelated to Annemarie's family due to her hair color, but Annemarie's parents are able to quell the suspicion using baby photos of Lise in which her hair was dark.
This is an instance in which Annemarie and Ellen had to conceal themselves from the soldiers; however, there are a number of events in the novel in which the two friends and their families and allies must lie or hide from the Nazis (this includes attending Great-Aunt Birtie's "funeral" and Ellen and her family hiding on Henrik's boat).