To have told DD she has to come to family day out regardless of how she feels?

Oh for fucks’ sake, the girl has disabilities beyond autism and needs a wheelchair. Are you always this nasty or is it just because you’re hiding behind a keyboard and don’t have to actually deal with the consequences of your words ?

You can tell DD that she has to come, but you can't make her! You could try explaining that her brother is very excited and would love to have her there, after all the HP things they did together. You could say that most of us do things we wouldn't choose for ourselves now and then, in order to keep loved ones happy, but that it shouldn't happen too often, and in future you'll take care to ask her before booking anything for the four of you. If all else fails, DS can go with one parent plus 2 friends while the other stays at home.

Can you bribe her with something? Simple but needs must, and it will likely work.

Acknowledge that she is growing up and you hope she will come along for DS sake and to acknowledge that she gets something she wants / wants to do as well.

She is autistic. As the mother of 2 autistic girls, I can say that it is probably not that straightforward.

@Blossomtoes she's autistic and also has other disabilities.
It wouldn't be "staying with a friend" it would be giving the responsibility for her care to the friends parent.
Not all adults would want to take on that responsibility.

Why can’t she spend the day with a friend?

Apparently she can't be left at home alone, so not really, she'll just have to suck it up, for the sake of her family, making a sacrifice for the ones she loves. Learning a valuable lesson that the world does not revolve around her needs and wants. Like everybody else on the planet.

That's great OP. FWIW i don't think you're favouring DS and your rationale does makes sense, but in terms of DDs feeling and reactions its what she think your actions are saying that matters.

I'd talk to her. Say it's very selfish to ruin ds's day and that she should change her attitude, go with a willing heart. I'd also talk to her about JKR Not being a TERF because that is factually incorrect and should be corrected.

My son is autistic. Once he goes off something, it is just totally a NO. He loved Paw Patrol when he was little but when he outgrew it, quite suddenly, he couldn't even cope with seeing the characters. They'd make him feel angry or uncomfortable. I can't rationalise it. It was a gut reaction from him.

I think you sound like you decided she should like it and you don't sound too open to hearing her pov, because you're going anyway. What struck me was that for years you have not gone because YOU didn't want to. It seems you have agency but your older child doesn't? Seems harsh.

Two members of your family aren't keen on going. Yet one member really wanted to go a couple of years ago. It didn't have to be a family day, unless you need help with transportation/care needs, then it does put you in a difficult position. Your DD will start to have interests that aren't appropriate for her younger brother and she might not want her Dad to tag along. So just consider her needs as she moves to adulthood.

One is the adult the other is a child. No wonder or young folk can't cope. Youngsters out of control when a teacher or police officers tell them to do something, it's bloody pathetic and downright dangerous. The screeching of "you can't tell me what to do" is heard all too often and all because of parents not parenting.

But why go when ds is the right age and dd is too old, rather than go when ds is the right age and ds is too young?

Tbh five years is a tricky age gap, it's going to be fairly rare for them to be into the same thing at the same time. So you're just going to end up with no one doing anything they're into if you insist you only to things they both like.

Have you made it clear to her you wouldn't have booked for anyone if you'd realised she no longer wanted to go? Sometimes what they hear isn't quite what we mean, she may still be thinking you're going because her brother wants to or even that you should have known she was no longet interested. I could see my middle boy getting hung up on the timing and wanting to know why we are going now when his brother's love it and didn't go when he really loved it.

My Autistic DD and I are very similar and very close and I've also spent years being her interpreter through situational mutism, but I don't always get it right and sometimes I realise after the fact and then I need to adjust and go back and change things. PPs idea of writing a list on paper and having her tick what the issue is, is that something that might work? There may be no deeper reason, but I'd want to make completely sure before we went.

I would have a conversation along the lines of
I guess you are feeling you are a bit old for this now. I wish looking back that I'd managed to take you when you were younger. Anyway, I reckon it will still be a good thing to do. What is the one thing that you would love to do at 15? I can maybe try to do that with you separately.
Also, let's have a look at the website and work out which bits you might enjoy.

Maybe agree to keep it off socials?

I agree with previous posters - the chances of an autistic teenage girl not having heard, over and over again, that JKR is transphobic and wants all trans people dead, is slim to none. Whether she believes that herself or not is beside the point - she would be worried about what her peers might say if they found out she'd done anything HP related. Maybe have that conversation and see what she says.

Ps, you'll like the films so so much more than you think you're going to too. I wish I could see them for the first time again!

I only got into Harry Potter as an adult and love it. It’s not just for kids but maybe she’s seeing it as a bit childish. I’d suggest you all make an effort to watch the movies together and make them fun movie nights with popcorn etc. It might bring her around if she sees both you and DH getting into it too. Also you will love them - the story develops as the films go on. Then your experience will be enhanced when you visit.

Whatever the intention, I certainly think it's possible that it is how she perceives it. Of course it might something else entirely. Either way, I can't imagine dragging an autistic teenager somewhere she doesn't want to be will be a great birthday present for any of them.

Make the effort to sit through the films, you will enjoy the day a thousand times more. Its basically a 3 hour walk around of movie props that don't mean anything to you otherwise . You can bond with your children over the experience better aswell.

Top top, take snacks and drinks incase the cafe is horrendously busy.

As for your daughter, she will really enjoy it. Unless she can give you a decent reason for not going I'd feel inclined to make her come along.

Gosh people are being hard on the OP. I can see she was genuinely trying to do something nice that the whole family would enjoy. People are making out like she’s some sort of cruel and selfish mother. Give advice in the situation but don’t make the op feel bad- she’s tried her best.
I couldn’t care less about HP but I still found HP tour fascinating. I don’t think it really is aimed at little kids like a pp said. There’s no rides or stuff like that.