Burger Chef WAS in the #2 position in the USA, with 1200+ restaurants.
As far any "return", Hardee’s can’t "return" a Burger Chef Big Shef (or any other sandwich, etal, for that matter) in a version of their own, and Still call it "Burger Chef".
I KNOW Burger Chef, came out with the Big Shef, LONG BEFORE McD came out with a Big Mac.
BigBoy (Azar’s, Bob’s, or Frisch’s)may or may not have had a similar sandwich, i’m really not sure, and if they did, I don’t know when it would have been first sold.
In any case, Whatever happened to BigBoy restaurants and their BigBoy burger (if thats what it was called) I don’t see any other Restaurant advertising BIG BOY Sandwiches, and if I did, I would expect the sandwiches to be made the BIG BOY Way. Especially if I seen a BigBoy
Image Advertising it.