His parents as given here in this locked MP with only one manager/curator, are without proof or evidence that I'm aware of.
My well researched source with cited references includes a very helpful genealogical chart for the family of Manasses, Bishop of Troyes (d. 991).
https://www.persee.fr/docAsPDF/bec_0373-6237_1925_num_86_1_448731.pdf
https://www.persee.fr/doc/bec_0373-6237_1925_num_86_1_448731
According to this source, "Origin of the House of Ramerupt-Roucy" by H. Moranville, published 1925 in the Bibliothèque de l'École des Chartes, volume 86, pp. 168-184 -- his parents were:
Dame de Ramerupt Hersende d'Arcis sur Aube
No children or marriage for the Bishop of Troyes is indicated. And his only sibling was:
Hilduin I d'Arcis-Sur-Aube, 1st comte de Montdidier, d’Arcis-sur-Aube et de Ramerupt
(We need proof of the validity of Berthilde de Nouvion en Ponthieu )
The children of the Bishop of Troyes' brother, Hilduin, 1st Lord de Ramerupt, given here as Hildouin II de Ramerupt, I. comte de Montdidier were:
* Hildouin III de Ramerupt, II. comte de Montdidier who married twice, once to Adelaide de Roucy
* Manassès, comte de Dammartin who married Constance de France, heritiere de Dammartin
* (And a sister, "Isabelle")
According to my source, the younger Hilduin (brother of Manasses of Dammartin) was both 2nd lord of Ramerupt AND 3rd lord of Roucy through his other marriage (since the name of the other wife is unknown, at the moment I haven't figured out which was first, although the birthdates of his children should be a great clue upon further investigation).
And there was no "Hilduin IV"...