Katherine Keats-Rohan in her Domesday People, book, has Willem Chieure (William Capra or Cheever) as the brother of Ralph de Pomeroy, and a sister Beatrice. Sibil is the only child mentioned and she married Robert II Burdet de Cullei.
I think if we should merge Le_Chievre-2 and Chievre-5, then we might be heading towards a better idea of who these people were.
I don't have time at the moment to look at the link Darlene has posted, so not sure how Goisfred fits in.