There are different types of joint custody but in all types, where the child lives is determined by the court is the parents cannot reach an accord. You can't "make" your son live with you in violation of a court order. However if he or the other parent is in violation of court ordered custody, you can file an action in court for contempt against the other parent. They may be fined and or jailed as a result and if the contempt continues, custody modified in your favor based on that.
An eighteen year old is an adult and can live wherever he or she chooses. A custody order has no bearing on this.
If the parents have joint legal custody, then Dad has an equal say. Even if they don't have joint legal custody, I would imagine that something such as this (allowing the child to move in with a friend) would be a sufficient reason for Dad to ask the court to award him custody, and he would likely have a very good chance of getting it.
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yes. you came under joint custody when you turned fourteen.
If you have Joint Legal Custody, then neither parent can physically change residences without the approval of the other. If, per the question, the daughter is living with the father, or the father has "primary" custody, then you can move wherever "you" want, at least in my perception.
Joint legal, and limit joint physical. see link below
No they can not choose until they are 18.
Physical and legal (with joint provisions if you so desire). However any custody modifications including who gets custody and relocation may only be allowed by order of the court.
If awarded joint physical custody.
you have to fight for custody
Yes.
Only by order of the court and/or the agreement of both parents, at least until the boy reaches the age of 18.