JRI-Poland records the death of Siegismund Rosenberg in Breslau in 1896 aged 72 years 3 months, so born 1823-24. It names his parents as Moritz Rosenberg and Philippine Loebel. JRI-Poland also records the birth of Siegmund Rosenberg to Moses and Philippine Steinauer on 22.11.1822; I assume these are the same person.

Siegismund and his wife Malwine were uncle and niece.

For more on Philippine Loebel / Steinauer, see his mother.