Premise: Andries Bonger (20 May 1861 – 20 January 1936), nicknamed "Dries", was Johanna van Gogh-Bonger's favorite brother. Bonger was a friend of his future brother-in-law Theo van Gogh in Paris. It was through Andries that Johanna and Theo met. He also knew Vincent van Gogh who called him André in letters.
Hypothesis: Theo van Gogh was friend's with a man who was referred to as André by Vincent van Gogh.