I am not a genealogist but this is cool to look up: Katherine Roet, dau of Sir Payn Roet is the third wife of John the Gaunt and is the widow of Sir Otes Swynford (Pedigree III, p. 12). She is found again on pg. 64 (Pedigree XVII) as Catherine dau. of Paen Roet, and again on page 607 (Pedigree CLXXIII). John has received his title as Prince and Duke of Lancaster and she is referred to as Lady Catherine (Roet) Swinford. Source: Americans of Royal Descent by Charles H Browning, Copyright 1882, Second addition 1891, Reprinted 2011.
There are many more pedigrees for Edward's line in the book to search through. The spelling variations are tricky-I would search the French derivations, to be sure.