Margaret, Marchioness of Namur was the daughter of Peter II of Courtenay and Yolanda of Flanders.
Background
Henry was the son of Frederic III, Count of Vianden (c 1160 - 1210), and Mechthilde (Mathilde) of Neuerburg (?). Another son, Frederick I, younger brother of Henry, inherited Neuerburg and married Cecilia of Isenburg, but that dynasty became extinct with the death of Frederick III of Neuerburg in 1332 (de).
Career
Margaret (called Sybille in some sources) married Raoul, lord of Issoudun in 1210. Their grandfather had received the county as an inheritance as a nephew of Henry IV, Count of Luxembourg (Henry I of Namur). Henry and Margaret continued ruling Vianden.
Henry V, Count of Luxembourg (1216 – 1281), maternal grandson of Henry IV, Count of Luxembourg (Henry I of Namur), invaded Namur and ruled it 1256-1264 as Henry IV (or III ?).
She died in Marienthal on 17 July 1270 and was buried there. Margaret and Henry had the following children:
Mathilde (c 1216 -), married around 1235 with Kaloioannes Angelos "Johann Angelus" (c 1193 - c 1255), Duke of Syrmia and Bacs.
They bore Maria Angelina (c 1235 - a 1285) whose husband Anseau de Cayeux or Chaurs worked for Charles of Anjou. Possibly they also bore Helen of Anjou (c 1236 – 1314), Queen consort of Serbia.
Peter, dean in cathedrals of Liège and Cologne (died after 1272).
Frederic of Vianden. Frederic died in 1247 (5 years before his father). Henry I van Vianden (d 1267), bishop of Utrecht from 1249 to 1267.
Philip I (d 1273), Count of Vianden 1252-1273.
Their issue was Godefroid I, Count of Vianden (d 1307 or 1310) and four other children. Yolanda of Vianden (1231–1283), still revered today in Luxembourg.