So the champion of those conferences if they do not make the CFP will be in the Rose Bowl (regardless of rematch or not). If the champion (and/or 2nd place team) make the CFP then the 2nd/3rd or highest finishing team from those conferences fill those spots.

Now if the champ is in CFP and they're looking at next best I'm sure if close in the polls and conference standings they could manipulate something to not have a rematch but honestly the Rose/Sugar probably wouldn't care if they got a rematch. And from what I understand the CFP committee doesn't actually make those selections/assignments because it is a contract with the conferences and the bowl (except for in years the Rose/Sugar are the CFP games).

Same goes for the Sugar Bowl and the SEC/B12...