On page 80, what was anja"s family forced to give up?

Anja's family were hiding the grandparents in their bunker. The Nazis wanted to transport them to Czechoslovakia to a special place for old people so they could be "better" taken care of. This most likely meant they would be killed. Anja's family finally had to give them up because the Nazis threatened to send Anja's parents if they didn't produce the grandparents.