You are able to move a student from one class to another. You will need to remove the student from Class A and add to Class B. The scans will show in Class A but you can MOVE the scans for that student from Class A to Class B. The scans will be with Class A until moved as that was the Class the form was scanned in, and if the form is specific to that Class A, it will only be scanned into Class A.
Please let me know if you have any trouble with this.