On waiting list, older sibling at school already.

[MrsMessi]

My older child y9 changed school mid year for various reasons. School app was already in for younger y6 child with 1st choice siblings previous school - very strict academy- as of course we did not know if sibling would be able to move or not. LA would not allow any changes to app post move. Older child transformed by new school and we want younger child to go there, both to be with sibling and also he has ASD (sen support only no ehcp) and older child feels strongly it would be better for younger- I trust him on this he has experience of both schools and is very perceptive. We are on waiting list for the school now with sibling priority. (I accepted the other school already as advised) The second round of offers is on same day as appeals need to be submitted- should we wait and see or start preparing appeal just in case.

[TeenTimesTwo]

You have nothing to lose by preparing an appeal.
Therefore prepare an appeal.

[admission]

The appeal process and any changes due to 2nd round offers / waiting list are two very different and separate systems. You should definitely appeal and your first reason is clearly the fact that elder child is flourishing at the school., which I am sure you can expand on.