Betje Benjamins was the widow of Philip Slier. Pictures of Betje Benjamins and Duifje and Debora Slier are published in D. Slier and I. Shine, Hidden letters, a glimpse of Holland during World War II(New York 2007) 104-105. A family tree of Philip Slier and Betje Benjamins is published in the same book on page 165.
In addition, a Jokos file (number 51744) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.