We ended up going back to the psychologist who did the WISC, and she is figuring out the extended norms out from his raw scores. He hit the ceiling (18-19) on several sub-tests (8 out of 12), which we didn't fully understand a year ago. Because he hit the ceiling on so many of them, we started to question what his "real IQ" actually is and whether or not it really matters.

Did you find with your dd that her extended scores were quite different from her original scores?