I think your daughter in very wise in not going on holiday w/him. After all, he is not her biological father and she may not feel comfortable going w/him the way he is acting at the moment. It wouldn't be appropriate to go off on holiday w/just him and her.
As to what to say when he asks about her and his invitation? Tell him that it is between him and her and that you are not going to be the go between for them. Your daughter is old enough to make her own decisions and he needs to learn to respect her wishes and have these type of discussions w/her.
BTW, none of us can actually say what truly goes on in their minds, but I would venture to say that his October holiday fell through or he may want to take your daughter on holiday and then say what a great time he had w/his step daughter and brag about it w/his new friends...again, no one can say what is up w/him these days.
Step back and allow your daughter to handle this situation between her and her step father. You've got enough on your plate, i.e., be there to listen to her and off her advice...but it is up to that grown man to learn how to communicate and to rebuild the bridge he destroyed. That is not your job....you were fired a while ago...remember?
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
