Melia,
This is a bit of a messy situation because the first school will migrate to being a primary school in 2012. I guess at that point it will become a 1 form entry primary school.
As such the current PAN of 36 is going to cause some problems in 2012 for the school. In effect they are going to have year classes of 36 as the current cohorts move up through the school. As you have no appeal date yet you presumably do not have the LA case against admission.
If I was making the LA case I would strongly make the point about transition, as no panel is going to want to increase a class of 36! That will in effect blow your case out of the water if they do use that arguement. Sorry.
However LAs are not always as on the ball as they should be in such matters, so PRH's comments are valid if they do not mention the transition to primary school. It maybe best to wait and see what the LA case says and then we can suggest if there are any others ideas.
I would mention that as there is a yr2/3 class with 28 in it that the infant class size regs will not be breached by the addition of one more pupil. It just pushes the panel towards being positive about the idea that we can admit because we don't have to consider the ICS Regs.
To me the weakest part of your case is your 9 year old daughter - the panel will think it is your responsibility to organise getting her to school. The use of grannie as adult taking would be stronger if it was everyday, but still not very convincing as per PRH's comments. Strongest parts are the extra capacity, the fact that the classroom can easily take 30 but only 28 in it and that they have had had more in the past - 32 in 2 classes now.
You need to talk about why you will be sending youngest to the school - 5 minutes walk is obvious but look for out of school clubs etc that you can mention and say you really would like your year 2 son to have the benefit of these as well. For the same reasons as above with 9 year old do not talk about 2 places at once, it will not be a positive it will detract from the case.