If the order granting you custody has been granted, then why would there be another hearing? If your ex wants to overturn the order, he'll either have to appeal or ask the judge for a re-hearing, which is rarely successful.
This answer is not to be considered a response to a specific legal issue in a specific jurisdiction - it is to be considered only a general response to a hypothetical scenario posed by the questioner. For specific legal advice, please consult with a licensed attorney in your jurisdiction.
If the default order has actually been granted, he has a very small window to ask the court to reconsider and set the custody hearing back in. If the order has NOT been granted and is just pending (i.e. your attorney filed the Motion for Default but the court has not acted on it yet), then it is possible that the other party might show up at some subsequent court hearing and ask that the motion for default be denied. Since you already have an attorney, these are the questions that you should be asking them.
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