I haven't got the answer on your question but did you know that after Sara's mother died in 1909 later the father Gerrit Koelman was deprived of his parental rights and Sara was send in 1911, together with 2 sisters and 2 brothers , to the children-home Zandbergen in Amersfoort ?http://www.waterlandsarchief.nl/index2.php?Itemid=185&op...
Zandbergen still exists and they still have the old files.
You could ask them for information. ( use the e-mail address in this link ) http://www.zandbergenjeugd.nl/index.php?page=oude-dossiers
Bye , Jan