The 6th Duchess of the Infantado was Ana de Mendoza, (1554 - 11 August 1633). The 7th Duke was Gomez de Sandoval y Mendoza, grandson of the 6th Duchess. The 7th Duke's mother Luisa was a daughter of the 6th Duchess's first marriage, with another Mendoza—Rodrigo de Mendoza—from this complicated family. It was not unusual for the Mendoza family, prominent since the last third of the 14th century, to retain the name "Mendoza", even with natural brothers and sisters and even where the most common patterns of the time would have dropped that surname, in such a way that one named "Hurtado de Mendoza" (as is the case here) names his son as "Lopez de Mendoza", while the brother was only a "Mendoza" and the daughters chose to be known as "Mendoza"; any other kind of name was added to Mendoza, using the names of mothers—Pimentel for example—or even grandmothers. (This was distinct from the present-day Spanish naming customs under which a person takes two surnames, the first from his or her father and the second from his or her mother.) This makes very difficult to track the lineage of the Mendoza family. An example of carrying a maternal name can be found when the name of the 3rd Duke is given in forms including "de Luna" or "de la Luna". His mother (the 4th Duke's paternal grandmother), was a María de Luna, the daughter of Álvaro de Luna, Constable of the Kingdom of Castile, beheaded in 1453.