I have another question... If I pursue a 504 plan, one concern I have is that it could change how DS is viewed. If he isn't tested carefully, he doesn't cooperate and gets spectacularly low scores. That gives a very different impression if what he needs from accurate testing.

If they will just accept my private testing as documentation, then it seems to me that would be fine. If they want to do their own testing, there s a very real risk if will not be accurate due to DS being stressed.

Do I understand correctly that we would just need documentation for a 504 plan, or would the school need to do their own testing? I know they require their own testing if I request any special education services. If they test well, there would be no problem with them doing the testing. If it's rushed and they don't build a rapport with DS, it would be disastrous (unfortunately, I know this from prior experience).