School were being unreasonable really, for not anticipating this.
If they weren't sure about needing an extra row they should have put the original chairs out further forward, with space for the extra row at the back.
Other parent needs to complain to the school if she feels she must, as once the extra chairs go out than they were bound to be a free for all to sit on them.
I can understand why they people who were there early felt aggrieved.
Our prize giving was yesterday. I was half an hour early, still not quite the first parent there, did get a front row seat but still couldn't hear most of what was said.
The head teacher refuses to use the microphone, despite being a school with a larger than average number of deaf and hearing impaired pupils and despite an announcement saying that there were a number of hearing impaired pupils and parents in the hall on that occasion (I am one of those parents and need to sit as close to the action as possible so I stand a chance of hearing and understanding even half of what is being said).
Although, to be fair, the other reason we couldn't hear anything is because one of the parents who arrived later allowed her three year old to run riot up and down the almost empty back row, pushing chairs as though they were cars and making driving noises and shrieking with either delight at her game or anger at any attempt to have her sit down.