NICOLAS d'Oisy, son of GAUTHIER [I] d'Oisy & his wife Ade [Ide] de Mortagne (-[1169/71]). The Chronicle of Alberic de Trois-Fontaines names (in order) "Nicolaum, Yvonem, Fastradum et episcopum Everardum Tornacensem" as the sons of "Galterum de Avennis" & his wife Ida[462]. The Liber de Restauratione Sancti Martini Tornacensis names "altero filio suo [=Gualterus] Nicholao", specifying that he succeeded in "castrum Avesniense et Bracbantum"[463]. The late 13th century genealogy by Balduinus de Avennis records that "filius eius Nicolaus Plukellus" succeeded "Walterus cognomina Plukellus"[464]. Seigneur d'Avesnes, de Condé et de Leuze. "Evrardus…Tornacensis episcopus" confirmed the donation by "Johannes advocatus Cisonii" to Cysoing, in the presence of "fratrum meorum Nicolai…de Avesnis et Gossuini advocati Tornacensis", by charter dated to [1174/86], confirmed after the donor´s death by "domna Petronilla uxor eius soror mea et Petrus supradicti Johannis frater"[465].
m (before 1150) as her second husband, MATHILDE de la Roche, widow of THIERRY de Walcourt, daughter of HENRI [I] de Namur Comte de la Roche & his wife Mathilde de Limbourg. The Genealogica comitum Buloniensium names "Mathildis" as daughter of "Henricum comitem de Rupe", specifying that she was mother of "Iacobum Avesnensem"[466]. The Chronicon Hanoniense names "Mathildem filiam Henrici comitis de Roche in Ardenna" as wife of "Nicholaus filius [Walteri…de Avethnes]"[467]. The Chronicle of Alberic de Trois-Fontaines names (in order) "Fredericus archidyaconus Sancti Lamberti Leodiensis, qui postea factus archiepiscopus de Tyre, et soror eius Mathildis" as children of "Albertus de Rupe", specifying that Mathilde married firstly "Theoderico de Walecurt" by whom she was mother of "Werricum de Rupeforti et matrem Theoderici de Hufalize, cuius filius Henricus de Hufalize", and secondly "Nicolao de Avenes"[468]. The late 13th century genealogy by Balduinus de Avennis records that "filius eius Nicolaus Plukellus" married "Machtildem filiam Henrici comitis de Rupe in Ardenna", whose first husband was "domini de Walecourt"[469].
Nicolas & his wife had [five] children