John Joseph Alden (goes by Joe) is the Boxcar Children's cousin. He is married to Alice, and is the adopted father of Soo Lee in later books. He is the nephew of James Henry Alden, as his father and James were brothers. He is an avid outdoors-man, and has experience working in the Alden Museum, and has a handy-man on the family island.
It is likely that his father's name also started with a 'J.'