Hello again and thank you for the additional situation. This makes a more sense to me now.
Since you have previously been repeatedly informed that the company/union would be using the 2002 seniority date, you would typically have an argument that you have "detrimentally relied" on that information provided by them and they should not be permitted to change the date now, at least not with regard to this RIF since you have had no time to prepare as other employees have had.
Detrimental reliance is an equitable theory used to prevent an injustice from occurring even if the contract does indicate that the later date should be used.
It would be best if you retained a private labor/employment attorney to communicate this to the union/employer in an attempt to resolve the matter in your favor. If they are not willing to avoid litigation by reverting to the earlier date, then the attorney may need to file a petition with the local court seeking to enjoin them from laying you off.
It has been my pleasure to assist you. Please remember to press the smiley faces/stars on the right of your screen when we are finished with our communication so I will be credited for my time. Kindly remember to ONLY rate my answer when you are fully satisfied. If you feel the need to rate anything less than OK, please stop and reply to me via the REPLY TO EXPERT or CONTINUE CONVERSATION button with whatever issue or clarification you may need. I will be happy to continue further and assist you until I am able to explain your concern to your satisfaction. Please also remember that I cannot control whether the law is favorable to you or not, so please don’t shoot the messenger.
Thank you very much and all the best to you,
Please feel free to bookmark the following link so you can request me to answer any future legal questions you may have: