Re: No second dog in Co op?
To put it in perspective: Think of it as a movie, not a game. Only one player can play the role of the Hero. If there Hero has family, obviously they can't put a clone of every other family member for the second Hero during Co-op. Also, I'm pretty sure that co-op will feature the same story as single player - again we can only have one "the Hero" of the story.
As far as I've gathered, "the Dog" will be just as much of a character as "the Hero" which will feature it's own plots and such, so again there simply is no way to put two "the Hero" and "the Dog" in the same storyline.
The universe would implode, simple as that. The time/space continuum couldn't handle it.