Just a quick update: Davidson will not perform the calculation, but they will accept a signed addendum including the missing index/indices.
I have received official confirmation from the testing clinic that my son's GAI was 149, and they are willing to issue an addendum confirming the same.
I am also curious about extended norms, given that he got perfect scores on both VSI subtests (confirmed by the examiner in the report, not just my assumption). In your experience, would any of his numbers likely come out higher if recalculated on extended norms? I don't think I'll ask for this, given that the original numbers already clear the bar in his pretty clear-cut 2e case, but I would love to know if you have any insight here. He was tested at age 5 and 7 months.
Thanks again for your help!
