1) Time pauses in the base neighborhood when you send a teen to college. You can go back and forth between the base game and college. Time will pause in the college neighborhood when you play the base neighborhood.
2) I just sent both of the Pleasant twins (Angela and Lillith) to college. I had each get on a phone separately and move to college. I will play Lillith separately, and then merge Angela with Dustin Broke (move one teen into a dorm and merge the second into the same dorm) into a custom dorm and play them at the same time.
