Of course in the letter you will want to be sure and specifically ask for all the new information.
The other thing to do is go to there previous school and play dumb. Ask the nurse to update the emergency card with your new cell phone or something. You will either be tokd they transfered or they will pull out the card and you may be able to comment on making sure they have dad's new number you have XXX, XXX, XXXX. You can get the prefix for the general area. If she says no, then oh well maybe that was just the friend the stayed with while moving what do you have.