In what year did Sigismund Casimir's mother die?
Sigismund Casimir Sigismund Casimir, Crown Prince of Poland (Polish: "Zygmunt Kazimierz Waza" ), (1 April 1640 – 9 August 1647) - was the only legitimate son of King Władysław IV and his first wife Queen Cecilia Renata. He was named after his grandfather Sigismund III, and uncle John Casimir.
Margareta of Celje Margareta of Celje (German: "Margareta von Cilly" , Polish: "Małgorzata Cylejska" , Slovene: "Margareta Celjska" ) (1411 – 22 July 1480) was a noblewoman member of the Slovenian House of Celje and by marriage Duchess of both half Głogów and Ścinawa.