In January 1836 Isaac moved from Colonnowska, Gross Strehlitz to Ponischowitz. Isaac's brother Abraham and his wife followed him in December 1837. In 1838, Isaac returned to Colonnowska, and in 1841 Abraham and his family followed him. The records of the moves in JRI-Poland identify the brothers' father as Joseph, and Abraham's wife as Rosel Prager. The 1838 record cites naturalisation number 2505 which indicates a descent from Josef Nothmann (see Josef's grandfather's page for the naturalisation numbers issued to the family members).

Jenny's marriage record names her parents as J.J. Nothman and Rosel Kornblum. Leopold's marriage certificate names his parents as Isaac Josef Nothman and Rosel Kornblum - with the "I" of Isaac being identical to the "J" of Josef.

Jenny's marriage to a Gassmann strongly suggests that her father is a grandson of Jesaia-Schaye Nothmann, the founder of the Nothmann family and brother of the founder of the Gassmann family. Given the patronym of Josef, and the fact that Jesaia's son Josef had a son called Isaac I assume that the latter is the father of Jenny and Leopold. This assumption is shared by a tree on geni.com.