Ancestral Roots has Stephen as son by the 2nd wife Alix, giving no marriage date for Theobald & Alix, nor birth date for Stephen.
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The following information was supplied in a post-em by Curt Hofemann, curt_hofemann@@yahoo.com:
Stephen "Le Sage" Count of Champagne & Blois
Mother: Alix de Crepi b: ABT. 1020 in Vexin, Normandy, France
The identity of his mother seems to be in debate:
I think... (the mother of Stephen) should be Gersende of Maine, Thibaut III's 1st wife. Stephen Henry was born in 1046 and Thibaut and Gersende did not separate until 1048. ES II:46 gives these dates and mistakenly indicates Stephen Henry to be the son of Gundrada. Also see M Bur *La formation du comte de Champagne* (Nancy, 1977), 199, 214-15 where Stephen Henry is stated to be the son of Gersende. [Ref: Richard Borthwick 30 Jan 1998 message to Gen-Medieval] note: I don't know why he refers to as Stephen as Stephen "Henry". As far as I know, middle names didn't come into use until centuries later... Curt
Research note 1: mother: Alix de Crepi [Ref: Weis AR7 137:23]
Research note 2: mother: Gundrada [Ref: Moriarty p117, Paget p58, Watney p110]
Regards,
Curt
Note: the separation between Thibaut/Theobald and Gersende maybe didn't officially happen until 1048, but I have a child of Gersende's 2nd husband who looks to be b. abt 1045.