GUY de Dampierre
m firstly (contract 2 Feb 1246) MATHILDE de Béthune

Guy & his first wife had eight children:
3. JEAN de Flandre ([1250]-Anhève 14 Apr 1292, bur Flines-lez-Raches). The Genealogia Comitum Flandriæ names (in order) "Robertum, Willelmum, Iohannem episcopum Leodiensum, Balduinem et Philippum" the sons of "Guido…ex Mathilde filia Roberti Tenremontensis"[684]. The Annales Blandinienses record the death in 1291 of "Iohannes, filius Guidonis comitis Flandrie et Mathildis de Bethunia eius coniugis, episcopus Leodiensis" specifying his burial at "Felinis" {Flines-lez-Raches, near Douai}[685]. Provost of St Donat at Bruges 1270. Provost of St Pierre at Lille 1274/77. Bishop of Metz 1279. The Gesta Episcoporum Mettensium (Continuatio) records the succession of “filius comitis Flandrensis dominus Johannes” who was later transferred “ad Leodiensem ecclesiam”[686]. Bishop of Liège 1282. A letter dated 13 Oct 1291 bears his seal[687]. The Biographie Nationale de Belgique records his death 14 Apr 1292 at Anhève but does not cite the corresponding primary source[688]. The early 17th century artist Antoine Succa sketched some details of his monument[689].
https://fmg.ac/Projects/MedLands/FLANDERS,%20HAINAUT.htm#Marguerite...