That sounds similar to what John Byrne did in his Elseworld series
Superman/Batman: Generations, when second-gens Kara Kent (Supergirl), Bruce Wayne, Jr. (Robin II), Hippolyta Trevor (Wonder Girl) and Wally West (Kid Flash) form their own superhero group. There's even a comment that the "Justice League" is a title they could still use as they grow older -- a not-so-subtle slam on TEEN Titans, perhaps?