Powys-Lybbe forbears
| Pierre de Grandson Seigneur de Granson ( - ca1260) |
John Tregoz Lord Tregoz (<1247 - <1300) |
| Agnes ( - >1283) |
Mabel Fitzwarren ( - <1297) |
m. ca 1285
| William Grandison Lord Grandison | Sibella Tregoz |
 b. d. 27 Jun 1335, Ob 9 Edw III . 1st baron. Of Ashperton, Herefordshire. |
 b. d. 21 Oct 1334 . Eventual co-heir. Younger dau. |
Children
| Piers Grandison Lord Grandison > Mabel Grandison < John Grandison Bishop of Exeter Otes de Grandison > Agnes Grandison < > Catherine Grandison < |