Back in 2017 I signed a patent contract with the company in which I used to work as one of the co-authors of an invention that was going to be patented in Europe. In this contract I was forced (otherwise I was going to be fired and I couldn't afford to lose my job at the moment) to renounce to any property over the invention. In turn the company compromised in the contract to recognize me as one of the author's of the patent. A while after I left that company, because my relationship with it wasn't the best . Today, they contacted me saying that I need to sign another document full of terms that I don't agree with, for them to be able to extend the original patent to United States. The difference is that this time they can't say they will fire me if I don't sign. So instead they are saying that my name won't appear as one of the co-authors in United States. Would this be possible? A patent with less authors in US than in Europe? Wouldn't they be breaking the first agreement they made to recognize me as a co-author?
Especially in the U.S., correct inventorship is important. Co-inventors are not strictly analogous with co-authors. In the U.S., all true inventors must be listed. An inventor is someone who makes a conceptual contribution to something that is claims. The only legitimate reasons to remove an inventor would either be for them to decide that you were listed inventor for EPO purposes (where correct inventorship is not as critical) but never really qualified as an inventor under U.S. rules; or for the one or more claims in the EPO version you particularly contribute to be dropped from the U.S. application.
Under the new (2012) AIA U.S. patent law, if the company has a signed papers from you agreeing to sign any and all required documents, they can do without your signature by swearing they tried to get you to sign and attaching copies of what you signed previously.