Сводный брат

Сводный брат (the step brother) is Jiren's stepbrother, and the strongest of all of Jiren's family members (not including El Tio, that guy is powerful) He is the one who is responsible for uniting all of the Jirens and summoning El Tio.

Backstory
Much like El Primo Сводный брат was spared during El Hermano's genocide. The difference being that he was more powerful than El Hermano, so he had no choice but to spare him. It is unkown who Сводный брат real parents are, or how he got that strong. Some rumors suggest that El Tio trained him, but he was sealed at the time so that wouldn't really make sense...