I was playing around with creating a new OD tonight. As far as rivalries go, whatever team you substitute for, you'll get their rivals (or whatever team is subbed for that rival). For the protected rivals, you have the option of having a cross-division rival that you will play every year. It's all or nothing for that, either everybody has one or nobody has one. So we could either change out our 12 teams for a 12-team conference, the drawback being that our conference rivals would be kind of weird. A team subbed for Texas, for example, would have several conference rivals, and other teams would not. If we did that, we'd probably need to go with protected cross-division rivals to make sure that everybody has at least one rivalry game. Other idea would be to replace crappy single teams from different conferences. This way we could all have a cpu rival, and if we wanted to also do a user rival, that could be done through the cross-division protected rival setup. This would also have the advantage of us not having to have a dynasty that's missing some of the best teams.