Ex-H and I book holidays within our weeks.
If he is planning a holiday that cuts into my scheduled time with the kids, then he has to offer me the equal amount of time he is taking from his allocated time. And I do the same back. We have to agree to what's being offered or propose a different schedule that works for each person.
If no proposals work, extremely rarely, then each person has to stick to their own scheduled time.
In essence, we swap weeks.
So in your scenario, when DD is back from holidays with "him", she starts a two week period with you, which means "he" does not get his contact week because he has already had it during your scheduled time.
I hope I am making sense.
Why isn't that the case here? He can't just book holidays in your scheduled time and then you lose out.
I am really sorry to write "he" "him" but I really thoroughly dislike him and would rather call him nothing.
Sending you 💐.
'This too shall pass'