Mike, that is a tough situation. I am a licensed attorney with over a decade of employment law experience. It is a pleasure to assist you today.
To be honest, what they are doing is fraudulent and should not be tolerated. I think you first need to notify the unemployment commission about what is going on and what you fear will be the tactic of your former employer to try to do away with or challenge your unemployment coverage. You can offer to sign a sworn statement as to what you believe to be happening. This offer will help lend credibility to your position.
If you want, thereafter, you can contact GM directly and tell them what is going on as well. I am sure they will be non to pleased about the situation. This would help protect your unemployment as well because you can show the unemployment office what you have stated to be true, if challenged.
It is a tough situation. That said, at the very least, you need to preemptively contact the unemployment officer and get ahead of the wave, so to speak, relative to him potentially challenging your unemployment payments.
I would not participate in the fraud they are perpetuating either under any circumstance. That could even result in criminal charges.
Let me know if you have any other questions or comments.
Please also rate my answer positively (three or more stars).
Best wishes going forward!