Henri de Buren was by all accounts betrothed to Madeleine Sillem, his first cousin and wife-to-be, before he left on his trip for the Americas. She was born in Mexico City in 1835, during the four year period that her father Wilhem was a speculator for European business interests there. Henri's voyage through Mexico was certainly made more agreeable thanks to his uncle, who was still well connected.
The following excerpt on Wilhelm is from Hans-Wolff Sillem’s website chronicling the Sillem Family.
Wilhelm (1804-1885) who had been an apprentice at Hope & Co showed more skills in business but developed into a reckless speculator. His "showpiece" was to grant the Polish government a credit of dizzying height: pre-financing the year's harvest. The Polish used the money to finance a campaign against Russia. The Tsar's empire prevailed and Sillem & Co went bankrupt. Father Jerôme was devastated, and not only because of the financial loss. After all, he had been the Tsar's court banker! Jerôme did not live long after that.
Wilhelm Sillem did not learn from the disaster he had caused. To the contrary: he continued to hope for profits from speculations. First he moved to London with his large family where he found employment in the firm run by his uncle Hermann Sillem. Wilhelm endured only two years in London. After that he tried his luck in Mexico. However, his business partners over there soon withdrew confidence after failed speculations. After four more years he returned to Hamburg as a failed entrepreneur.
Backed by his well-to-do mother, he started with two new projects. In a side alley in the city he built 17 houses for wealthy people. Nine years later he had sold only 9 of them. His brother Adolph Sillem took over the remaining ones and put them on the market. Then Wilhelm had Germany's first glass-covered shopping passage and a hotel built on Hamburg's splendid boulevard Jungfernstieg. The public response to "Sillem's Bazar" was enthusiastic at first. However due to inconsiderate errors of judgment on Wilhelm's side the wealthy clientèle began to stay away after some time. Already after 40 years the hotel and the passage were pulled down and replaced by new buildings. Both projects had failed. The family had lost lots of money. They stripped the speculator of his legal capacity. He was granted a fixed annual sum and urged to leave the city.
With his wife and children Wilhelm moved to Geneva and spent the remainder of his life there. He got deeply involved in public welfare caring for the poor and shared what was left of his fortune with the needy in the city. They called him "Father of the Poor", and a street was named after him. His son Wilhelm Sillem (1842-1904) became an agriculturist. He migrated to Argentina with his family.