Hasn't anyone noticed by now that with this management team and the IAM led Association if it's not in writing then it's not binding. A handshake goes nowhere these days. The signing bonus was in the company's proposal. That's all it was, a proposal. We now have a agreed upon T/A. It's not part of the T/A that we will be voting on. Unless a letter of agreement signed by both parties is released then the company has no legal obligation to honor what was in their proposal or agreed verbally over a cup of coffee.
Stop thinking old school. I'll be waiting for a letter or correction added to the T/A on the signing bonus. Until then it doesn't exist legally.