GUILLAUME de Louvain, son of GODEFROI VII Duke of Lower Lotharingia, Duke of Louvain, Comte de Brabant & his second wife Imagina van Looz (-after 1 Aug 1224, bur Abbaye de Villers). The Oude Kronik van Brabant names "Wilhelmum de Parwiis" as the child of "Godefridus" and his second wife "Ymaynam, filiam comitis Lossensis"[154]. Heer van Perwez en Ruysbroek. "Henricus dux Lotharingiæ…et Willelmus frater meus" donated "terram de Ruschebruc" to "canonicorum S. Jacobi in Caldenberga" by charter dated 1201[155].
m (before 1206) as her first husband, MARIE d'Orbais, daughter of ENGUERRAND d'Orbais & his wife --- (-after 10 Apr 1233). Her parentage and marriage are confirmed by the charter dated 23 Jun 1242 under which her son "Godefridus dominus de Parweys" confirmed donations to the church of Sainte-Catherine de Milen made by "avunculo meo domino Gotberto de Brul et a domino Ægidio filio suo de Herge"[156]. The primary source which confirms her name and her second marriage has not yet been identified. She married secondly (before 1231) Baudouin le Karron.
Guillaume & his wife had [seven] children
http://fmg.ac/Projects/MedLands/BRABANT,%20LOUVAIN.htm#_Toc280448701