Do try and think slightly wider than one frigging disco for 4 year olds.
We adopted my daughter at the age of 9. Her schools will have been in receipt of Pupil Premium Plus for her since social services first became involved with her birth family. Some of that will have been spent on her and on other pupils with PP or PP+ but the majority will have been spent on stuff that benefits them and other pupils in the school (on average).
Your daughter has at least one parent who loves her and is competent at parenting to the point where you will sit and refresh your expensive device to get her a ticket to a disco. My daughter had parents, and then a foster carer, who neglected and abused her and her siblings. My daughter was never put first in anyone's life at any point. My daughter's schools were her refuge. We are the first people - relatives or professionals - to truly put our daughter first in her entire life. She had all her formative years of maltreatment. You don't think that that deserves a bit of the playing field being evened up occasionally? You don't think that has a lifelong impact?
It's fair enough to be ignorant of what PP is, but once you have it explained to you, surely to God you could use your imagine just a little bit? Does it not give you pause for thought that the people on this thread who work in schools are universally in favour of giving PP pupils a leg up? How would it be if this disco was the only opportunity your daughter was going to have in the whole school year to have this kind of fun? You can't imagine it, can you, because you're a 'good enough' parent (as social services refer to it).
Separately, I'm a PTA member and I can tell you that when these type of restrictions are put in place (the capacity limits) it is always for a reason. If you don't like it, I suggest that instead of complaining about it, you contact your PTA and offer to volunteer occasionally, or do anything to help whatsoever. You might find it eye-opening and certainly educational. And frankly, if you don't like it - don't buy a ticket.
It's people like you - and many others on this thread - that make it a soul-destroying thing to do, being involved in a PTA. And somehow all the ones who complain are those who you know for sure are never, ever going to contribute anything to school life beyond their own precious darling.
If I'd come to this thread earlier I'd likely not have had such a harsh response but so far you've had the likely reasons for the capacity restrictions clearly explained to you AND the likely reasons for the way the PP kids' attendance is being handled. Yet somehow you still persist in feeling hard done by.