According to FamilySearch …
https://ancestors.familysearch.org/en/L44C-YRY/baroness-matilda-dei...
Sir Edmund Deincourt, 8th Lord Eyncourt & Isabel de Mohun were the parents of Maud de Bermingham who married William de Bermingham, II
Can anyone provide more substantiation one way or another?
Phillip Lee Gibbs brought to attention.