More information is necessary to answer your question. If the divorce was in Florida, it would have been necessary for your mother to have been served with a Petition for Dissolution. There is a procedure for service by publication, but that entails a sworn affidavit from the Plaintiff/Petitioner that he made extensive efforts to locate her and was unable to do so. Once that is done and approved by the court, service by publication can be done.
However, if he filed a false affidavit, and if she has just found out about this, she can and should raise the issue IMMEDIATELY. If there was an affidavit, from the facts you relate it would have had t be fraudulent, and a fraudulent and bad-faith affidavit would document that the court never had jurisdiction over her to decree a divorce.
If they resided in a different state, that state's law would control.
Either way, she should get to a divorce attorney IMMEDIATELY to investigate the situation, and what really did occur.
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