Yes. See links
The parents have assumed joint custody.
no
He has every right to go back to court to petition for joint custody, yes.
That should be expressed in the custody orders.
The rights your ex-husband will have once you divorce will all depend on what the judge rules. He could have joint custody or split custody.
If your husband has joint legal custody he can contest you moving the child form the state where you share custody
They had irreconcilable differences. They have joint custody of their one son, Sam.
No, but you can ask for joint custody of them. see links
Any legally married couple has the same rights if they obtain a divorce. The issue of joint custody of the children would be decided by the court depending on certain factors that include the laws in the particular jurisdictions. Some favor automatic joint custody, others evaluate the relationship between the parties to try to determine if they can get along well enough to make joint custody work to the benefit of the children. You should consult with an attorney in your jurisdiction who can review your situation and explain your options.
If there is a divorce with two children and joint physical custody has been ordered by the court, does each parent have a right to claim one child per year? This generally has to be addressed by the court, but joint physical custody does not necessarily mean equal physical access. He parent with the children 51% of the time can take the deduction, minus any time spent in day care and/or school. A true form of joint physical custody is Bird Nest. see link below
As for Joint Custody of Them. See Bird Nest link And remember - you are not losing either parent.
Unless you adopted your wife's children, you should not be required to support them after the divorce.