According to the FMG Medieval Lands database (also see the Northern France MedLands pages and the Burgundian MedLands pages, Ermengarde was the daughter of Rainard Comte de Bar-sur-Seine and his wife (name unknown). She probably married both Héribert IV Comte de Vermandois and Milo IV Comte de Tonnerre.

ERMENGARDIS

Regarding her identity and possible marriages to Heribert IV de Vermandois and Milo IV de Tonnerre:

• "Comes Heribertus" names "materque mea Pavia…pater meus Otto, eius genitrix, avia mea Ermengardis" donated property to Notre-Dame de Homblières by charter dated [13 Jan/13 Oct] 1045[1467].
• According to Ernest Petit[1468], Ermengardis was the widow of Milo [IV] Comte de Tonnerre. The author highlights a charter of Ermengardis Ctss de Vermandois witnessed by Renaud Comte de Tonnerre. He suggests that Comte Renaud would only have done this if he were the son of Ermengardis, although other explanations must be possible.
• Settipani points out[1469] that Ermengardis is named as the wife of Héribert [IV] in a document of her father-in-law Albert [I] Comte de Vermandois, relating to the abbey of Homblières, dated some time between 982 and the death of Comte Albert (in 987).
• According to Ernest Petit[2100], Ermengardis married secondly Heribert [IV] Comte de Vermandois. The author highlights a charter of Ermengarde Ctss de Vermandois witnessed by Rainard Comte de Tonnerre. He suggests that Rainard would only have done this if he were the son of Ermengarde, although other explanations must be possible. Settipani points out[2101] that Ermengardis is named as the wife of Héribert in a document of her father-in-law Albert I Comte de Vermandois, relating to the abbey of Homblières, dated some time between 982 and the death of Comte Albert (in 987). If the two marriages apply to the same Ermengarde, Comte Héribert must therefore have been her first husband and Comte Milon her second.
• However, it is not clear that this suggested co-identity is correct, a simpler explanation being that there were two different individuals named Ermengarde. "Raynardus comes Tornodorensis pagi et mater mea Ermengardis comitissa" donated "alodum nostrum…Cappam" to Saint-Michel by charter dated 1002, signed by "Odonis vicecomitis…"[2102].
• Ernest Petit also suggests[1470] that Ermengardis (wife of Comte Milon) was heiress of Bar-sur-Seine, in order to explain how her granddaughter by Comte Milon, Eustachie, transmitted this county to her husband Gauthier de Brienne. He identified the father of Ermengardis as "Renaud Comte de Bar-sur-Seine" based on two charters, which he dated to 992 and 997, which name "Rainardus comes" whom he identifies with Rainard, son of miles Raoul de Bar, who is mentioned in the Chronicle of St Bénigne[1471].
• A family connection is indicated by the charter dated to [992/1005] uner which “Milo comes Tornodorensis castri” donated property "in villa…Curtis-Secreta" to the monastery of Saint-Michel, with the consent of “coniugis mee Ermengarde et carissimorum filiorum meorum Achardi, Rainardi et Alberici”[2098], the property being the same as the subject of the [992] charter witnessed by "…Raynardus comes…"[2099].
• There appears to be no other evidence of the existence of this person, and Bouchard[1472] points out that the dating of the two charters in question is uncertain. She suggests that it is more likely that "Rainardus" is identified with Renaud Comte de Sens or with "Rainaldus" son of Ermengardis. This of course leaves open the question how Bar-sur-Seine was transmitted to the Tonnerre family.

Comte Heribert [IV] de Vermandois & his wife had two children:

a) ALBERT [II] ([985/90]-[1 Feb 1015/1017]). The Gesta Episcoporum Cameracensium names "Alberto Vermandensi comiti, fratri Ottonis"[1473]. He succeeded his father in [1000] as Comte de Vermandois. He abdicated before 15 Jul 1010[1474].

b) EUDES [Otto] ([985/90]-25 May 1045). He succeeded in [1021] as Comte de Vermandois.

MILO [IV] Comte de Tonnerre ([950/65]-1002 or after) & his wife had four children:

a) ACHARD de Tonnerre

b) ODO de Tonnerre

c) RAINARD de Tonnerre ([980/90]-after 16 Jul 1039).

d) AUBRY de Tonnerre

-------------------- Died after 1018

She had a sister named Beatrice. She had a half-brother and four half-sisters, named Renaud, Gerberga, Maud, de Macon and Agnes