What is a company required to disclose during an ERO? I feel that my retirement plan has been invalidated. Do I have a valid grievance?

I have been employed 18 years by Company A which provides contracted IT services to Company B. Company B publicly announces that it has decided to stop outsourcing IT services and move instead to an in sourcing model. Company A announces looming companywide cuts and issues an ERO but does not disclose that it is already negotiating with Company B to transition in employees. Since I qualify for the ERO, I read the distributed material and follow the online decision making processes. Based upon the information I choose to not accept the ERO since I am not actually ready to retire and I was not notified that my job was in jeopardy. After the ERO offer expires, Company A announces that an Employee transition agreement has been worked out with Company B. The agreement provides no consideration for prior service year credits with regards to future retirement offers. We are also informed that if we refuse the transition offer we are considered a voluntary separation with no severance..