Most often disagreement over visitation is not addressed until there is inadequate time for the aggrieved party to have a judicial determination made resolving the conflict. Unless the Order of Dissolution is clear, there is often disagreement over major holiday visitation including Christmas, Thanksgiving, 4th of July, Spring Break (Easter) and extended summer vacation. When there is no direction in prior orders of the Court, the parties should communicate their plans early to avoid later conflicts.
If conflicts arise, the parties should try to work out a reasonable schedule. When that is not possible, court involvement may be necessary. When the parties have taken an unreasonable position or suddenly changed their minds after having once agreed to the plan of the other parent, the court gets a picture of inappropriate parenting. If the circumstance is severe enough, the court may change the primary custodial parent. Since this is a drastic step, it is best to seek legal advice before taking independent steps which may include approaching the court.