...to ask if your kids are going trick-or-treating and how on earth do you organise it?

[Velvetbuzzsaw]

Like it says on the tin.
How do you organise a trick-or-treating night out for DCs. DD (11) has been left out by her friends group that she usually hangs out with. I was pleased that the transition to Y7 was going well and she had made new friends. Now one girl from her Junior school (where DD was horribly bullied and excluded) has invited DD's friends group, but not her, over to her house for snacks then to go out trick-or-treating together. DD asked if she could come and was told she could "wait for them in the alley". Obviously I said not to bother with that.
I didn't used to have time for Halloween, DH thinks its an American import and a commercialised waste of time. But the DCs enjoy it and love dressing up and, well, it was rather a lot of fun last year . Now it seems we must hide in the house with the lights off since DCs haven't been invited to go trick-or treating Darn these mean schoolgirls

Just take them both out instead?

They dress up and you take them out instead

Just take them and ask dd if there is anyone else she would like to bring

My 2 never really went out in group. To begin with I went with them and then they went together by themselves

I’d take her out with adults. I ignore groups of children without adults.

Yes take them out and ask her to invite someone else to come along.
We are lucky in our estate that all the kids tend to go together in a group, they are all different ages and at different schools. No one gets to dictate who can and can’t tag along.