Steady the increase in subjects was in cc where missling explained it was a fda request in order to balance the 2 age groups - as you said, years 5-11 and 12-17. I can’t find the quote.
If the drug works across the entire patient population regardless of age, then the expansion isn’t necessary. The point of the expansion was so that they could do a subset analysis by age, but that is only important if the drug doesn’t show good enough results across the whole patient population. The only way to know if it’s working across the entire population is once the original 64 complete the trial, peak at the data. Totally reasonable.