"Who is that man, Ms. Walken?"
"That is my dear half brother Eduardus. My father had four legitimate children, but his youngest, Eddie, was the only one to reach out for me in need."Eduardus Limette Black (1820-1899) was the youngest son of Nigellus Black and Eudokia Black. He was banished and banned from the family for finding contact with his eleven years older illigitimate half-sister Alexia Walken Black in the 1850s.
Being born 10 years after his sister Phoebe, he never attended Hogwarts with his siblings but was sorted in the same house: Slytherin.
He was 5 and 8 when meeting his sister Alexia for the first time and looked for her for many years untill 1853 when he found her and comforted her in America with her mothers death. He was burned from the family tree and suddenly had no income, so he said goodbye to Alexia and moved to Sweden.
There is no source indicating his marriage or any children. There was a claim in 1914 of a lunatic who claimed to be his grandson from a daughter named Alice Black but this was claimed untrue, as the man had no mother with that name or a DNA matching Eduardus's.