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Assuming this is a civil order ex wife obtained as opposed to a criminal order obtained by the prosecuting attorney, then your wife could get the order modified for the wedding day. In other words, she would need to have an additional order entered in Utah ( by agreement with the ex) that says it is not a violation of the old order for ex husband to have contact with ex wife ( be within 500 feet or whatever limitation is on the original order) on such and such day while participating in the wedding celebration of the son.
I would think a personal appearance in Utah court would not be necessary, but she will need to submit a detailed supporting affidavit or declaration under oath laying out the situation - convince the judge that her request is reasonable.
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