Superman Family: The Blonde Caped Crusaders

During the early days of Superboy of Earth-One and Superman of Earth-Two, a pair of courageous blonde hair troubleshooters joined them in their crusade against crime, and each would eventually adopt costumes similar to the Boy and Man of Steel.

Superboy's childhood pal Pete Ross, was the nephew of a revered Scotland Yard inspector of Earth-One, following in his footsteps in helping uncover mysteries and helping the oppressed. Pete learned of Clark's secret, while witnessing his transformation during a camping trip. As such, Pete had on several occasions assisted his buddy by creating distractions that allowed Clark Kent to become Superboy. This led to Ross being invited to the Legion of Super-Heroes as an honorary member. He even masqueraded as Superboy on occasion such as to protect him from his Revenge Squad. On another occasion, Pete gained the powers of his pal due to the machinations and manipulations of young Lex Luthor, while Superboy was left temporarily powerless.

At the same time that the Superman of Earth-Two appeared for the first time, protecting the citizens of Metropolis, another hero debuted half a continent away. This was the wealthy young oil baron known as Tex Thomson, who found himself battling various threats around the world. He would eventually be accompanied by his pal Bob Daley, and after a couple of years both decided to became masked men. Tex became first Mister America and then  the Americommando, while Bob became Fatman. This new identity necessitated Tex dying his hair black to complete his disguise as well as creating a special mechanism within his cape allowing him to fly. It was around this time that Mister America met and worked alongside Superman, as both were members of the All-Star Squadron.

Pete's son Jonathan later learned of Superman's alter ego, and had a few adventures alongside him when learning of his dual identity. When aliens kidnapped Jonathan, there was strain between the two men as Pete resented the fact that Clark didn't protect his son. Using a device created by Lex Luthor, Pete transplanted his brain into the body of Superboy from over a decade earlier, bringing him to the future to fight his former friend. When Superman defeated this hybrid Superboy with help from his pet and his younger self in Pete’s body, he had Ross incarcerated in a mental institution until he could save Jonathan and reunite him with his father. 

Tex's older son Tex Jr., who had been raised by his mother, ended up joining the Boy Commandos in the late 1940s. Meanwhile, Tex Sr. returned from his spy mission in Europe during World War II, and legally changed his name to George Tompkins*. Soon after, he met and married Lucille Lane**, and together the couple had a daughter Susie who had several adventures in the late 1940s and early 1950s with Lucille's sister Lois and future brother-in-law of Superman. The former All-Star Squadron teammates Mister America and Superman were now brothers-in-law George "Tex" Tompkins and Clark Kent, cementing their relationship.

* There is precedent in the Superman Family for a family changing their legal name to protect its members from evildoers, as the parents of Earth-One's Lex Luthor changed their last name to Thorul. Lex's sister and the Luthor's daughter Lena Thorul became accustomed to this name as a young girl. Like Lena, Susie was unaware of her father's true family name until possibly later in life.

** Another example of how, just like Tex Thomson became George Tompkins, Lucile's Earth-One counterpart Lucy Lane adopted the alias of Sandra Rogers while her beau Jimmy Olsen briefly went by the alias of Magi the Magnificent.