OK, I've got my Monday morning head on, so have to ask how I screwed up what I wanted to say so badly ?
I said if we tell her to come, we pay, and it's not counted as holiday.
Our policy has been to replicate the sort of normal policies we've had at work. If an employer sends you away from home, he foots the bill, and it's not holiday even if it's a nice place.
I did say (though apparently with not enough emphasis) that one should not use the power of an employer to force them to give up holiday.
We've tried to make working T&Cs as similar to fair ones we've work under ourselves.
From feedback we've had from nannies, that's surprsingly not the norm. We've heard of curfews and intrusion into their private life. Arbitrary and stupid rules, and ignoring the expertise in the subject they get from first hand experfience of your child.
We see our nanny as someone doing a critical job, occasionally under non-trivial stress. Also if they live with you, it's harder to leave it all behind. I'm big on human factors when managing people, and I know that without a break, your performance simply degrades, occasionally quite catastrophically.
Thus even if your nanny wants to come on all your holidays, I'd be relcutant to do this, regardless of the legalities you must leave it all behind or go at least a little loopy.