Kurš apprecējās ar Euphrosyne of Opole?

Euphrosyne of Opole (Polish: Eufrozyna opolska) (1228/30 – 4 November 1292) was a Polish duchess and regent.

She was a daughter of duke Casimir I of Opole and his wife Viola, Duchess of Opole, and a member of the House of Piast. She was Duchess of Kuyavia from her first marriage to Casimir I of Kuyavia, and Duchess of Pomerania from her second marriage to Mestwin II, Duke of Pomerania. She acted as regent of the Duchy of Kuyavia during the minority of her son Władysław I the Elbow-high in 1267-1275.

Mestwin II (Polish: Mściwój II or Mszczuj II) (c. 1220 – December 25, 1294) was a Duke of Gdańsk Pomerania, member of the Samborides dynasty. He ruled Gdańsk Pomerania as a sole ruler from 1273 to 1294.

Casimir I of Kuyavia (Polish: Kazimierz I kujawski; c. 1211 – 14 December 1267) was a Polish prince and a member of the House of Piast. He was Duke of Kujawy after 1233, ruler over Ląd from 1239-1261, ruler over Wyszogród after 1242, Duke of Sieradz from 1247-1261, Duke of Łęczyca after 1247, and Duke of Dobrzyń after 1248.

He was the second son of Konrad I of Masovia and his wife Agafia of Rus. He was probably named after his grandfather, Casimir II the Just.