Blanche de Tregoz Grandison, of Switzerland - Alternative Data After Merges

Blanche Grandison of Switzerland is my 22nd great grandmother

This is in error. Sources need to be provided. Two wives of (a) William/Guillaume de Grandison seem to have been merged into one, mistakenly. A William de Grandison, Sire de Grandson & Ste. Croix, married Blanche de Savoie (Savoy) and a William de Grandison (probably the same one) also married Sibyl or Sibilla de Tregoz, heiress of Ewyas-Harold in Herefordshire. Sibilla was never "of Switzerland" and was not born nor did she die there. She is buried in Herefordshire.

The Grandisons (Grandsons) were Lords of Grandson Castle in Neufchatel, Switzerland but seem to have been subjects of the English crown.