Sources

1) Source: Chronica Magistri Rogeri de Houdene "[1199] It was also arranged, that Louis, the son of the king of France, should marry the daughter of the king of Castille, the niece of Richard, king of England" (Data from secondary evidence)
2) Source: Chronica Magistri Rogeri de Houdene "[1200] it was agreed between them, that Louis, son of the king of France, should take to wife the daughter of Alphonso, king of Castille, and niece of John, king of England... After the conference, John, king of England, sent his mother, Eleanor, to Alphonso, king of Castille, to obtain his daughter in marriage for Louis, son of Philip, king of France." (Data from direct source)
3) Source: Chronica Magistri Rogeri de Houdene "Accordingly, on the fourth day they produced a writing, in which was the following statement: “king Sancho the Fat had three sons, Ferdinand, king of Castille, Ramiro, king of Arragon, and Garsias, king of Navarre and Nagara. Ferdinand was the father of king Alphonso, who took Toledo, and was the father of queen Vracha, who was the mother of the emperor Alphonso, the father of king Sancho, whose son was king Alphonso, who married Eleanor, daughter of Henry, king of England. Ramiro, king of Arragon, was the father of king Sancho, who was father of king Peter and king Alphonso. King Peter died without issue, and was succeeded by his brother, king Alphonso, who took Saragossa. Garsias, king of Navarre and Nagara, was the father of king Sancho, who was afterwards slain at Penaflel: he was the father of Sancho, who died without issue when a child, and was succeeded, in Navarre and Nagara, by king Alphonso, his father’s kinsman, who took Toledo, as far as the boundaries of Puente la Reyna and Sangosa: and the said child was succeeded by Sancho, king of Arragon, his father’s kinsman, in the remaining portion of Navarre and Pampeluna.”The Treaty and Covenants entered into between Alphonso, king of Castille, and Sancho, king of Navarre."