You and your ex-spouse spent the time drawing up a comprehensive parenting plan that covered such issues as drop-off arrangements, where the children go for school vacations and backup child care. It is your turn to have the children for an upcoming holiday, but now your ex wants them.
What are you to do?
Turn to the parenting plan
Your parenting plan should have a section that addresses how schedule changes should be brought up and decided. For example, perhaps a request to change a holiday arrangement should be put in at least a month before the holiday, and it will be discussed between the parties at the time.
Of course, these guidelines are not always followed.
Perhaps your ex pays child support diligently and found out only two weeks before Thanksgiving that his or her favorite sibling whom the children have not seen for years will be at the family holiday gathering, so you get only two weeks' notice. The intention, in this case, seems honest; no one is trying to purposefully take time away from you for the heck of it. Often, it pays to be as flexible and collaborative as possible. Who knows when you might need a favor in return?
As long as the request is not malicious and is made for a good reason, consider granting it. You can certainly ask for something in return--getting an extra holiday in the future, perhaps.
When requests are unfair
When requests are unfair, and they certainly can be, you are well within your rights to turn to the guidelines spelled out in the parenting plan and say something such as, "We agreed to give each other a month's notice for any schedule change requests." If there is a persistent history of unreasonable requests, you may feel more comfortable using your attorney to communicate with your ex (or with your ex's attorney). The reality is that some divorced people try to use their children to manipulate and punish an ex.