Well, it would be an alt-daughter of an alt-king of Castile, since @Kurt_Steiner will be very glad to know that no Trastamaras.Maybe an alt daughter of Henry III?
Breton match is possible, just wouldn't be OTL Fransez I (see trees about Brittany above)Francis I of Brittany?
Couple of questions regarding this tree (and the Berri/Breton ones attached to it):
Marie of Burgundy (sister of Jean sans Peur, OTL countess of Savoy, since her place has been taken by Jeanne de Valois)
Philippe the Good of Burgundy needs a second wife (Jacqueline of Holland is already spoken for, unfortunately), and his daughters need husbands