If you are thinking you might be on the chopping block, do yourself a favor and read this article.
16 Key Issues In Negotiating An Employment Severance Package
https://www.forbes.com/sites/allbusiness/2018/04/14/16-key-issues-in-negotiating-an-employment-severance-package/#393cea5176b2
Agreed. Try a lawsuit next. See where that gets you at an "at-will" state like MI.
Ay2, go in there and tell them "I decline your offer because it is insufficient. Come back to me when you have something better to offer". Be sure to let us know how it turns out.
There is nothing to negotiation... sign the papers and leave