This is what I, taking into account my personal situation of course, would do:<p>- Make it clear to the co-founder that the business will be between much more likely and 100% likely to shut down if they maintain this complaint. While this seems like it&#x27;s showing them the power they have, it&#x27;s much more important to show them how fragile the value of any shares they have are.<p>- Make an offer between the original offer and 100% vesting. Make it cash heavy if you can, possibly contingent on funding. Make this offer exploding - they need to decide within 1 week and if they don&#x27;t, you will pull everything except what you feel legally required to put on the table (the vested stock only, no benefits, no severance) and fight this.<p>This will drag on and kill your company if you let it, and settling could work. If settling doesn&#x27;t work, you&#x27;re in a new position, but you need to get this in a position where it will be resolved or not resolved quickly. Then you will know what you&#x27;re dealing with more clearly, but you are not left with the binary choice you think you are.