I just found this, which is slightly different:

http://www.nagc.org/index.aspx?id=2455

"Despite these limitations, testers should consult the Extended Norms if a child achieves at least one scaled score of 19 or two of 18 and modify scaled, Composite, GAI and Full Scale IQ scores accordingly."

Using that criteria (explained in way more detail on the link), it would seem that our daughter's score should be evaluated on the extended score.