For what it's worth, my feeling is that it's probably not worth pursuing this argument.
I don't see how you can win on "legal" grounds. If you raise the previous Adjudicator's opinion, the presenting officer will almost certainly trump it with the latest opinion, and point out that everyone has to abide by the rules as they are. My understanding is that an appeal panel cannot get involved in what the admission arrangements are, unless something has happened that is clearly unlawful.
If you had been disadvantaged as a result of a sudden and unexpected change in the rules for this year, you might possibly get a bit of sympathy from the panel (assuming they're human
), but from what you say, nothing has changed.
I would also be inclined to steer clear of this argument because of a separate point that I know you are thinking of putting forward, i.e. that from your own experience the 11+ does not always "get it right".
Normally, when appellants start questioning the system, or talking about a sibling ("Our other child passed the 11+, and we think this one is much brighter"
), the alarm bells start ringing, and I would advise "Don't go there!".
However, speaking for myself, if I were on your appeals panel I think I might be receptive to your experience of the system, based as it now is on three children. On its own it wouldn't win you the argument, but at worst it shouldn't do any harm, and at best it might elicit a bit of sympathy, especially if the presentation has a "light touch" - is brief, reasonable and non-dogmatic. (Not suggesting you would do otherwise.
Quite rightly, you've indicated that you intend to focus on your daughter. What I'm saying is that, if you wish to question the system in passing, then I wouldn't risk making more than one such point!
Just my view. Hope it helps.