GUILHEM de Urgell, son of ARMENGOL [IV] "él de Gerp" Comte de Urgell & his second wife Adelaide de Provence Ctss de Forcalquier (-Avignon 1129). "Adalais comitissa Fulcheriensis et mater mea Adalais et filius meus Willelmus marchio Provincie" restored "mediatem…castri…Lurs" to the bishop of Sisteron by charter dated 1110[755]. Monfar names "Guillermo" as the son of Armengol [IV] by his second marriage, citing no primary source on which the statement is based, and adds that he inherited his mother´s property and was called "conde de Niza"[756]. He succeeded his mother as Comte de Forcalquier.
m GERSENDE d'Albon, daughter of GUIGUES [V] Comte d'Albon & his wife Regina [Mathilde] ---. The primary source which confirms her parentage and marriage has not yet been identified. 1152.
Comte Guillaume & his wife had two children
http://fmg.ac/Projects/MedLands/PROVENCE.htm#_Toc274990139