According to Jaime de Salazar y Acha, followed by other authors, among them, Gonzalo Martínez Diez, they married in 1100, and with this ceremony their son was legitimized and declared heir of the Kingdoms of León and Castile. For Salazar y Acha, Zaida and the fourth wife of Alfonso VI, Isabel, are the same person, "despite of the impotent efforts of later historians to try to prove that she was not the Moor Zaida", and, accordingly, she would also be the mother of Elvira and Sancha Alfónsez. Another reason the author mentions to support this hypothesis was that shortly after the marriage of the king with Isabel, his son Sancho begins to confirm royal charters and, if Isabel and Zaida were not the same person, the new queen would not have allowed the new protagonism of Sancho in detriment of her possible future sons. He also cites a charter from the cathedral of Astorga dated 14 April 1107 where Alfonso VI grants some fueros and acts "cum uxore mea Elisabet et filio nostro Sancio" (with my wife Isabel and our son Sancho). This is the only document where Sancho is referred to as "our son", since in others he only appears as the king's son even though Queen Isabel also confirms the charters.