To exclude one from sleepover?

YANBU. It's not your responsibility to get someone else's child used to sleepovers. It's not fair for you to be expected to take her home in the middle of the night. It would be different if it was a one-off and not known in advance, but the expectation of this happening continually isn't on.

Honestly? I’d just let her try. Poor kid, some people just struggle with sleepovers more than others. I was one of those kids and if I’d been excluded from a group sleepover that would have been very hurtful.
Why not go on the assumption she has been working on it and wants to manage to stay. And support her accordingly? Are you really going to be having an early night whilst they’re all awake anyway? No. So is it really that much of an issue if she needs a lift home? No.
However I would have a low tolerance for it in that if she begins to get upset she just goes home- or a yellow card type thing. One reassurance thing only but then just right home or collected at 10 or whatever. Don’t let her spend the evening back and forth or building it all up.
Shes only young and positive support could help her manage this and be so chuffed with herself. In saying that, 3/4 of mine haven’t been able to do sleepovers easily and yet one moved out age 18 and the other age 19 and function just fine as independent adults. Despite “missing” residentials etc.

One solution would be for A’s mum to host the sleepovers.

Another would be to tell her mum that you aren’t going to take her home. I know that you will still be inconvenienced but I think if she has to do that she will make the decision that her daughter isn’t ready for sleep overs yet herself.

If you exclude her, you will inevitably look the bad guy regardless of how upset she gets and how inconvenient it is to you. It might also have a knock on effect on the friendship generally

I would talk to the mum. I would explain that you are happy to try again with the sleepover situation but you cannot take her home in the night and she needs to perhaps talk to her daughter about checking the time and deciding how she feels. Have a cut off point for example 9pm. If she thinks at this point she will not cope with the night, her mum needs to get her.
My children went to Beavers and they did this, anyone saying they felt homesick, poorly whatever it was they would keep til around 8pm then call home to tell you they aren't settling for whatever reason and you had to collect them as they didn't want any disruption in the night (from sad children to waking parents).

Quite old for this I would be concerned if I was her mum. There are usually several year 6 and 7 residentials

I wouldn’t try it again sounds like there’s been a fuss more than once already.

The mum is really out of line here. It’s one thing if this happens unexpectedly but when it’s a pattern of behaviour it’s unfair lumping that on another parent. A decent parent would be mortified and would go and pick their kid up not pester and emotionally blackmail the op to recreate the problem over and over again.

I’d say if it happens again the mom has to get her and uber or whatever transportation home and I wouldn’t do it anymore. Enough is enough. That’s ridiculous

Perfectly reasonable. Just tell the Mum what time you want her collected. Eg 7pm.

Personally, I'd probably still go ahead but the other mum needs to collect her if she doesn't stay - even if it means in the dark with other child.

But even if other mum will collect, OP can't relax and enjoy her evening or go to bed when she wants to in case this girl gets upset.

Does she go on sleepovers at grandma's/auntie's or go on school residentials? You could say she could come again shen she's successfully stayed away from home somewhere else.

I would offer if you can to take her at a time appropriate to you, otherwise say you have tried it hasn't worked and she either stays the whole night or not at all

There is so much endless understanding people can do the tap has to be turned off at some point and yes I would say this about my own child if it was needed

Have you tried a sleepover that is just A coming and no other friends? Would this be less stressful for A? Then you could progress to more friends - just a thought

I would invite her and say that she needs to make a decision about whether she feels happy to stay the whole night by a certain time. 9.30/10 pm She may be different this time if some time has passed since the last sleepover. But I think you would be reasonable in saying you don’t want any dramas after a certain time, one that is not too late for mum to collect her.

Yes. OP seems to be getting some pleasure out of excluding this child.

Personally, I'd probably still go ahead but the other mum needs to collect her if she doesn't stay - even if it means in the dark with other child. If she's offering then take her up on it. I do think it could be a little bit mean to exclude especially if the mum says they are working on it.

Is the upset getting any better at least with each sleepover, or is she just as upset each time? If she's not actually coping any better with each one then that might change things and I'd just go with leaving before bedtime until she's a bit older.

It’s not a punishment, just an alternative get together, given that she has said she wants to continue to invite the friend, and you clearly would prefer not to.

When was the last sleepover? If it wasn't recent, I'd be willing to try it one more time but if it was unsuccessful again then I'd be firm and insist she must be picked up at 9 or whatever time you think is suitable.

Have you tried having a sleepover with just A - especially as she is your child’s best friend?

That might be less overwhelming for A and a good warm up for larger sleepovers.

You don’t have to of course but would be nice and might solve your issue.

Why?

There's only one child who has a problem with sleeping over, so it's for that child's mother to sort.

It's not for the OP to ban sleepovers.

Yes but if you make the mum take responsibility for her own child, perhaps she'll stop insisting her child should stay at yours.

Once it starts to inconvenience her, she'll probably do the sensible thing and tell her DD she's not ready for sleepovers just yet.

Why should the other kids miss out because one can't hack it?

This.

Does A's mum host sleepovers? A, may feel more confident having friends sleep as hers than sleeping at friends, at least initially.

If at yours, I would have a specific time A's mum is scheduled to collect her, so it's clear.

Tell her dm she can come when she has been to therapy. Yewr 6? Hell's bells....
Or she can host the sleepovers...

I think I’d just pack in the group sleepovers for now. Have a few over for pizza/movie/whatever, but they all go home at 9. Or have just one over to stay.