If the father wants to move out of state, and the mother is in prison, those sound like sufficient reasons to justify a modification of custody petition on the basis of "substantial change in circumstances." Obviously, this is just my general opinion, based on the facts provided.
I advise that you contact a family law attorney in your area who can better advise.
You should consult with an experienced custody attorney. If you have true joint physical custody, and the mother is in prison, you may be able to move immediately by seeking an emergency petition.
I am exclusively a family law attorney, practicing primarily in the metro Atlanta, Georgia trial courts. However, I handle appeals from anywhere in Georgia.
This requires an experienced lawyer. Ultimatelty it is up to a court but certainly it is possible that a court reviewing the facts would find reason to change custody. Details, such as what the mother is in jail for, and the fitness of the father, and language of the current order, all matter.
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