Juan Manuel, Prince of Villena
However, Juan Manuel, Prince of Villena (grandson of King Ferdinand III of Castile and contender for the Regency of the Kingdom) and his wife Constance of Aragon (daughter of King James II and in consequence Blanche's maternal aunt), insisted to King James II that Blanche and her mother remain in Castile under their protection. Several historians believed that the real purpose of Juan Manuel to kept his sister-in-law and niece under his control was to secure the support of his father-in-law King James II in his fight for the regency, and in the same time, managed Blanche's inheritance.