You likely should review your parenting plan carefully to see what rights you actually have.
The parenting plans I have seen usually specify that only if scheduling for vacations conflicts would the parent with precedence gets to choose. I have never seen a parenting plan that gives one parent the power to decide when the other parent will have a vacation. What you seem to be stating is that you are not planning to take a vacation at the time the other parent plans to take his vacation.
You can review your parenting plan with your attorney to see what the provisions of the parenting plan are.
You might want to use Google Scholar to find "Marriage of Rideout" which is a cautionary tale for a primary parent who didn't want to let the kids go on a planned vacation with the other parent. It is a well written decision, and good law in WA.
The mom's decisions cost her thousands of dollars.
Hope this helps. Elizabeth Powell