Bertha Reens-Cohen is the sister of my grandfather George Cohen (he died in 1936).
GenLias has the marriage record for Bertha and Louis Reens
Huw 12-12-1923 Oldenzaal #61: Louis Reens 30 jaar g. Amsterdam, beroep Meubelmaker (Joell Reens, beroep Schoenmaker en Elisabeth de Jong) en Bertha Cohen 29 jaar g. Oldenzaal (Samson Cohen en Carolina ten Brink)