I can understand why you thought a performing arts school would be good for a child with high music ability but if you had 2 children with equal academic ability and one was particularly good at music, would that child be disadvantaged for being good at music and lose out to the other child withour music ability for the grammar school place?
The appeal I mentioned was turned down on 'no reason the child could have done better on the day'.
If we had two children, equally good academically, and there was only 1 physical space we could squeeze them into, we would have to find some way to choose. If one child showed an exeptional talent - be it music, sport, creative writing - whatever, I would be likely to choose that child.
I often make a note on my summary notes of any major talents the child may have just in case such a situation arose - but if it did, we'd be re-examining both sets of appeal papers, the clerks notes and our own, just to make sure we didn't miss anything.
Ater each appeal, I also tended to make a note of if I though the appeal should be allowed (Yes, Possible+, Possible, Possible-, No) - but we always go through all the appeals after we've heard the last one, and sometimes my views on a 'no-hoper' will change. One appeal was a 'Possible-' yet after a full & frank discussion, we allowed the appeal.