Geni has him married to her 'half-sister' of the same name: Isabella, Countess of Bedford
However according to Cawley, King Edward III only had one daughter by the name of Isabella. She married Enguerrand VII de Coucy, KG, 7th Earl of Bedford
It is noted in this profile under discussion, Isabella Plantagenet that she is fictional. "Elizabeth of Suffolk" her alleged mother, also appears to be completely baseless if I'm not mistaken. Very confusing.
Here is the source quoted on Isabella "Plantagenet" and her mother, Elizabeth of Suffolk's profiles. I'm not sure what to make of it.
https://www.google.com/books/edition/The_History_of_the_Reign_of_Pe...