I don't know if this is an option for you or not, but the staff at DSs current school (who are accelerating him) has been gracious enough to offer to speak to the staff at the new school, should it be necessary. I most definitely appreciate the offer and will give the new school their contact info when we arrive and register. I even asked the principal her thoughts on how I should approach the new school with the info and everything that's taken place this year and she was very helpful.
I don't know if your current school would work with you in the event you do need to change schools, but just a thought. Good luck.
