Interfere or not?

I've a dilemma.

On Saturday, my teenagers had some friends over. They are teenage children of my Brussels friend, but she had gone back to Brussels. When they were living in Dublin, 8 years ago, the kids were all good friends. It was lovely to see how well they got on together on Saturday. I invited them for lunch i.e. a few hours, but they reluctantly left at 9pm to go back to their grandmother's, where they were staying until their Dad got here Sunday.

My own 2 seemed genuinely sad to see them go, and they had made an arrangement for the 5 of them to go to the cinema on Monday. There was a bit of friendly teasing going on between them, especially trying to pair off my boy with one of the twins (all 13 year olds!). My daughter and the older sister of the twins were joking about being sisters-in-law!

Anyway, today I was going off shopping, and asked daughter had she made contact re the cinema outing- "no". I urged her, out of politeness, to do so, and she promised she would take care of it. I returned a few hours later to find she had done nothing, and to be told there was no need for me to be involved, that it wasn't anything to do with me - though she wasn't especially rude in saying this.

Now my problem is this- I think it's rude to make arrangements and not follow through. In fairness, they didn't contact us either. And I'm trying to let them make their own arrangements as far as possible- maturity, responsibility and all that. And I don't know how much of the arrangement was a joke "date" between my boy and the twin.

Do I keep out of it, just let them at it, or attempt contact myself tomorrow???