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You should get in touch with the attorneys who brought that class action and see if it is still possible for your father to join that class action lawsuit. If that case is closed, they may be able to give you other relevant information. You shoulw immediately consult your own attorney to protect your legal rights.
You father may have rights that are involved in the class action suit. Take immediate steps on his behalf to find out what those rights might be. I agree with Mr. Mashal.
The attorney that brought the class action suit is obliged to inform you of what is going on. Phone the attorney that represents the class.
Good luck to you.
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It is impossible to tell from your summary (1) where the lawsuit was filed, (2) whether it defined a state-wide or nationwide class, (3) whether the class action lawsuit was ultimately certified as a class action, (4) if so, whether your father is a member of the class that was certified, (5) if so, whether your father was required to "opt-in" to the class, and (6) if so, whether your father actually did opt in. At this point, the best way to proceed would be to contact the attorneys who filed the class action to determine whether your father is part of any certified class. From the sketchy information provided, your best bet would be to run various Internet searches in hopes of finding the lawsuit that you are referring to.