I would imagine OK and Texas would be in different divisions so that there would be the possibility of a OK/UT matchup in the championship game. They would still hold the Red River rivalry every year as a cross over rivalry game but the BIG XII will do everything to protect OK/UT and increase the chances of one of them representing the conference in the college football playoff.
OK, OK St, Cinci, UConn, WVU, Iowa St
Texas, TT, Baylor, TCU, Kansas, Kansas St
Think this would be more in line with what the Big XII would do IMO. Have to protect their cash cows above all and this creates a Texas division for all the Texans to drool over.