It's indeed a bit confusing that you have the same question on the Gelderland board.
You stated that your grandmother's ( Maria Petronella ) siblings died young except Sara.
On the link I send you I see that 3 children died young in Ilpendam.
Of the 5 children that went to Amersfoort the 2 brothers Gerrit died in 1924 and Cornelis in 1927.
Cornelis was married and had 2 children Catharina Elisabeth Wilhelmina born 1924 , died 1926 and Wilhelmina born 1925.
The sister Maria Johanna , died 1930 ,was also married and had also at least one child Gerrit Bernard , born 1930.
Still no trace of Sara so you still can use that link I send you to ask what happened to her after she left the child-home Zandbergen !
Bye , Jan