Not so much a party but I have been to a couple of "play day" events and met people either one to one or in very small group.
Events were fine for changes at one the organisers had people who were happy to do this for you (but only wet ones allowed) and the other you either needed a CG with you or maybe someone might offer if they liked you.
Yes at both events there were people with their diapers exposed so you could see when wet and some who maybe aren't yet used to just going had that "peeing" look on their face, changing was always in a private space though.
Yes I used mine freely without fear as I always do wherever I am, and at the first event I ever went to I did eeventually get brave enough to ask the organiser for a change, short story for that...
I was still very new to exploring littlespace and although I had talked about it with a number of people I had met at fetlife munches and communities like this I had never been to an event and only met one other AB in person, I had also not had a nappy changed by anyone else yet. The one other AB I had met before this had offered to drive me down there as he was coming past my city to go to it himself.
The organiser had told us at the start if you don't have a CG to come and find someone with a badge and they can change you or point you to someone who will and I was nervous about asking. So I was wet, like a lot! I had been putting off asking out of nerves.
Eventually I reached a point I knew i wold get leaky and was at the time playing near the guy that brought me, he noticed me wriggling and asked if I had been changed yet, I said no I'm a bit scrared to ask and he grabbed my arm and dragged me sheepishly up to the organiser.
Him: "Miss L!"
Her: "yes can I help you boys?"
Me: "umm yes miss, I ummm... could I..."
Her: (looking at me intently and then feeling the back of my diaper) "oh sweetie you're ready to explode, you need a change, would you like me to help you?"
Me: (feeling very small and like my cheeks were on fire) "umm if that's ok?"
Her: "sure honey that's why I'm here, lets' go and get your bag now and I'll take you upstairs" (turning to the other guy) "do you need one too?"
Him: "no miss I've just had one, my friend was just nervous to ask"
She led me off to get my things then took me to the changing room put a mat down and told me to lay down and just calmly got on with changing me, was very good at it, reassuring all the way and joking about how full I was.
In all an amazing experience.