Anoa’i goes by Roman Reigns in WWE and while he and Johnson are not technically related they refer to each other as cousins due to a close bond between the two families that have worked in professional wresting for generations.
The closest we get to Hobbs & Shaw starring actual family of Dwayne Johnson, is the role of brother Mateo, played by Joe Anoa’i.
The Blu-ray also reveals that the character of Mateo actually had lines in the movie at one time, though they are all cut from the final edit.