Employer Provides Incorrect Health Plan Info

[Guest Ms. Kate]

An employee would like to enroll on the company medical plan though open enrollment closed effective December 31, 2009. She waived enrollment at that time because she had decided to stay on her husband's employer plan. She has now found out that her husband's employer provided him with outdated benefits information upon which they relied when evaluating his plan against our plan. Her medications on his plan have now become significantly more expensive than they would have been on our plan.

Assuming our insurer will not allow her late enrollment -- and I doubt they will; she has a serious health condition -- what is her recourse against her husband's plan administrator? I believe the other plan violated its ERISA obligations?

Does anyone have any input they can offer?