Without more information, this is quite hard to answer.
First, normally the Court where the decree was entered is the proper court to ask to modify the decree, but with a child involved, you must look to the home state of the child, typically defined as where the child has lived (domiciled) the last six months.
Second, many states have high hurdles to cross to do this type of thing, because it is so hard on the child. For example, a man can be adjudicated to be the father even if he is not the biological father, and there is nothing he can do to change that under some situations.
Third, this is going to affect child support. Just an aside really, but something to think about.
You really should speak to an attorney in the state the child has lived the past six months. Set up a meeting and take that decree with you. Explain the situation. Good luck.
Talk to an attorney where you reside. Does the divorce decree name the child? If not, then the decree would not have to be amended. Are there issues regarding child support? Paternity? You are raising some interesting and important questions. You need to talk to a local attorney where you reside. Good luck to you.
Assuming your Divorce Judgment was in Michigan, you would have to file a Motion to Amend Divorce Judgment, and serve your ex-husband with a copy. If you are represented by an attorney, the court has discretion to allow you to testify by telephone. If your ex-husband will cooperate, you could try to file a consent order with the court. It is not clear from your question as to why you need to do this. Why not file for paternity of the child in the state where the child presently resides? I suspect that any court that deals with the paternity of your child, will want to make sure that the biological father of your child acknowledges paternity, so that someone will be on the hook for child support. Good luck to you.
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