You can change the pets boarding room by going to Calendar on the left hand side and then clicking run transfer.  From there you will select the date that the reservation starts.  Click on the pets name and drag and drop them to the room you would like to move them to.  If you select a room that has more than one pet you will be allowed to move only one pet or all when you drag and drop them.  At that time you can choose to only move one day or click the box to move entire stay of boarding.