San Francisco de Borja, IV duque of Gandía, was also a composer. Works attributed to him are: the 1551 liturgical drama Visitatio sepulchri, a Mass and a Ludi paschalis. The 16th-century inventory of Tarazona Cathedral choirbooks attributes to the Duke of Gandía the motet Exaltata in a lost manuscript; see Document 16/4 (1591)  in the following link: http://hispanicpolyphony.eu/node/16492
Juan de Borja y Castro was a nobleman and diplomat; he was the third son of San Francisco de Borja y Aragón, IV Duke of Gandía. He was the dedicatee of the manuscript B-Bc 27086, compiled in Vienna between 1577 and 1579, while Juan de Borja, I Count of Mayalde, served as mayordomo mayor of the Empress Dowager Maria of Austria, Philip II's sister and widow of Maximillian II. Juan de Borja was the Duke of Lerma's oncle.