What do I do?

[MoiraRosesMeltdown]

This is the type of situation I struggle with as a parent.

The girls in DD2's class have been invited out bowling by her friend's mum. Three of them are going. DD1 (8) was very excited.
I got a text today inviting DD1(10) too since someone else's sibling is going. DD1 is desperate to go.
But, DD2 doesn't want DD1 to go and is now refusing. I said to go ahead and refuse, and that her sister would go alone. DD2 is now crying because she wants me to tell her sister not to go.
The way I see it is that DD1 has done nothing wrong so I don't feel I can disappoint her. DD2 shouldn't get her way own way for being difficult, but she was so excited before that I don't want her feeling disappointed either.
I'm working so can't go. I don't want to risk DD2 (can be very moody and difficult) being grumpy for the other mother.

Absolutely dd1 should go, dd2 should go too though as she has committed to the outing. Do they normally get on?

Bit confused by your post. How old is each DD? Which DD was originally invited?

Dd1 is 10, dd2 is 8, dd2 was originally invited

I agree with the PP - I think they should both go. If DD2 really refuses, that's up to her - but I bet she'll go and end up forgetting all about it once she's there.

Thanks for all the advice. They are both going!