The family first settled in Frederick William's Duchy of Magdeburg in the city of Halle upon Saale, whence it adopted its surname.

Ferdinand's elder sister Auguste (1799–1883) married Johann Christian Söhle [de] (1801–1871), the son of their father's partner in the bank.

Blümchen Gottschalk's sister Amalie (1777–1838) was married to Baron Ludwig von Stieglitz, court banker of Alexander I of Russia.

[5] The Beit Din inflicted the ḥērem on Mendel Joseph Haller and, as was the law, prompted the secular authorities to execute that ban.

[5] Already for quite some time Mendel Joseph Haller was inclined not to observe Jewish law and looked for a solution to live an enlightened life, as he described to Allermöhe's Pastor Karl Johann Heinrich Hübbe[6] in a letter on 30 May 1805.

[7] Without pious devotion to Christianity, but vaguely acknowledging Lutheranism's supposed offer to live a life as he described, Haller delicately explained to Hübbe his wish for a fast and secret conversion.

[8] On 26 June 1805 Hübbe baptised the Hallers, with the parents adopting altered first names, Elisabeth instead of Blümchen and Martin instead of Mendel,[9] and their children Nicolaus Ferdinand and his elder sister and brother Augusta (Auguste) Clara and Wilhelm Ludwig, all taken place far out of Hamburg in the Trinity Church of Allermöhe [de].