Bartholomew Columbus was an Italian cartographer, explorer, cosmographer and the brother of Christopher Columbus. He helped plan and accompanied his brother on several voyages, including the fourth. Bartholomew was involved in many of the expeditions. In fact, in 1484, Bartholomew visited the King of England to show him a map of the areas around the world that he and Christopher wanted to explore.
Fernando Columbus was the second son of Christopher Columbus. His mother, Beatriz Enriquez de Harana, never married Christopher. Fernando accompanied his father on the fourth voyage as a crew member when he was about 14. After the death of Christopher Columbus, Fernando and his older brother, Diego, journeyed back to the New World in 1509 for several months. Fernando later stayed in Spain and became a scholar, collecting a personal library of more than 15,000 books. He also wrote his father's biography.
Diego Columbus was the oldest son of Christopher Columbus and accompanied him on the second, third and fourth voyages. After his father's death, he traveled back to the New World with his brother, Fernando, but instead of returning to Spain with his brother, Diego became the governor of the Indies in 1508. He made several trips back to Spain throughout his life to fight for the rights to the land that his father explored.
In addition to family, the fourth journey included about 150 crewmen and several captains. Diego Mendez was one of the captains who chartered a caravel in Jamaica to return the crew back to Spain after Columbus's ships were damaged too badly to make the trip back home.