There is support for Mathilde’s seen at French Wikipedia. But I think there’s chronology / family mixups, because the article (above) seems to suggest Arnoux de Granson is from a different family then the previous counts of Chiny.
https://fr.wikipedia.org/wiki/Comte_de_Chiny
Google translate:
According to Dom Calmet, Arnold or Arnoû would be in the strict sense the first count of Yvois or Chiny. He had married Mechtilde or Mathilde, daughter of the powerful Duke of Mosellane Ricuin. At his marriage, he allegedly obtained the erection of the county by his protective godfather, Duke Frederick, brother of Emperor Otto and the Archbishop of Cologne, Brunon. The eldest son of the noble couple would not be, according to this Lorraine tradition, other than Count Otton, the one whom the count dynasty named Otto I of Chiny.
https://fr.wikipedia.org/wiki/Otton_Ier_de_Chiny
Otto de Warcq was the founder of Chiny County, although he probably did not carry its title, and died around 987.
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That does not agree with Otto I, comté de Chiny sourced as dying 1013.