I run into this issue a lot with my clients. Both parents have to understand that the children live with them during their time-sharing. It is not a vacation or visitation as it is improperly referred to. If the children have school activities or extra-curricular activities or even want to spend time with their friends- that is part of the normal "growing up" process and both parents will be involved in it during their time-sharing period. To answer your initial question, legally, a child can decide whether they want to go to the other parent's house when they turn 18. They definitely have some say before that, but their opinion is not and should not be determinative before that. You want to make sure that you are still encouraging a relationship between your children and their father. My suggestion would be to discuss the issue with your ex (without the kids). Take a look at your final judgment or settlement agreement (it's probably been a while since you really read through it) there is usually a paragraph about extra curricular activities. If his actions or inactions are not in conformity with the judgment/agreement show him and if he continues not to comply you can file a motion for contempt. If there is nothing in your agreement/judgment to address the issues that are coming up then you may want to file a petition to modify.
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