Overnights and vacations are not apart of the visitation schedule in the decree.
What does your final agreement say about visitation?
It is what it is.
Is he nearby?
Is he wanted to take DD on vacation? Will someone else, (that you trust with DD) be there?
If he asks with no specifics regarding where they are going, who with, etc.. NO way.
I would refer him to the legal language of your agreement and leave it at that. If he rages, contact your L.
First, expect the batshit crazy rage. Then there is no element of surprise. Second, say no in writing and keep a copy of it and whatever his response is. Third, be very neutral and say "you agreed to X. A week is not in our agreement and I don't think it is in daughter's best interest."
Then, while listening to rage part 2 label everything he's saying/doing in your head blame, bully, curse, whine, complain, deflect, etc. and when he finally winds down say "I'm sorry you feel that way. If you want more visitation you're welcome to have your lawyer contact my lawyer to try to work something out." Then make him go bye-bye.