Complex sentence: Juan's mother was Inés de Garabito y Lanuza, his brothers were Martin, Sieur of Plasencia and Bardallur and Ferrer, Sieur of Azaila and Cosculluela, and his sister was Dianira, who married Pedro de Luna, Sieur of Illueca.
Split into simpler sentences: Juan's mother was Inés de Garabito y Lanuza, his brothers were Martin, Sieur of Plasencia and Bardallur and Ferrer, Sieur of Azaila and Cosculluela. His sister was Dianira, who married Pedro de Luna, Sieur of Illueca.