But this is not a crossover between those two TV shows.......
Well, Norton probably never mentioned his brother because he was the black sheep of the family, always on the wrong side of the Law.
We've seen Ed Norton's brother on TV. But he wasn't in New York City - he was part of the criminal element in Gotham City.
He was the arch-villain known as "The Archer".
And his name was Ed Norton.*
It's not unheard of in Toobworld. My favorite example would be the two Arthur Dales as seen in several episodes of 'The X-Files'. (Although we never met her, they also had a sister named Arthur Dales, and allegedly a dog by that name as well. I've always pictured Frances Sternhagen as being that third Arthur Dales.)
But the two Ed Nortons didn't exactly have the same name. Ed Norton, who worked in the sewers and was married to Trixie (real name = Thelma), had the full name of Edward Lilywhite Norton. It's my belief that the Archer was Edmund Norton and probably the younger of the twins.
Edward & Edmund.... rather Shakespearean, isn't it? Or if you prefer, Blackadderish.
As for Edmund Norton's middle name, I'm going to suggest "Archeron", but "Archibald" will do as well. And that he went by the nickname of "Archie" to avoid any confusion with his brother.
Archie Norton may have been the smarter of the two brothers, with a predilection for classic literature of derring-do. And because of that interest, before live-action role-playing games became a regular past-time, Archie Norton took an interest in archery, just like Robin Hood in the old legends.
But as I mentioned earlier, he got himself in trouble with the Law. Instead of repenting, however, he fully embraced his dark side and pursued a career as the Archer.
And that's why Ed Norton never mentioned him to his friend Ralph Kramden......
*Of course, this is all supposition on my part, but it keeps me off the streets.......