What do we think the chances are that "The Legion of Super-Heroes" from Adv. 247 would have ended up being a Marvel family story? Featuring either Mary or Freddie?
On the one hand, writer Otto Binder was working more for Fawcett, though on the other hand, he also did work for DC simultaneously, and it's not clear whether the basic Legion story idea was from him or Mort Weisinger, so it's very possible it still would've ended up as a Superboy story.
It's interesting to consider the alternative though.