Hero and Aced are the same way, granted they are also on the same network as Carbon. I think, but not sure, that there is America's Card Room and Lock. I don't have either of them, so I am not certain about that.

As for freerolls, I would say the best would be through here, for the merged network (Carbon, Aced, Hero), but I've also cashed in it 3 times, so i might be a bit biased lol