Failure to contribute to eligible participant’s SEP

Client and client’s wife have two related/affiliated businesses (S Corp). No other employees. Client contributed to SEP account for himself through one business, but failed to make contributions for his wife who was employed by the affiliated business. Accountant would like to correct this error, which occurred over three year ago, by “reallocating” a portion of the husband’s original contribution from his own SEP to his wife’s SEP. I do not believe the original contribution was in excess of contribution limits for the husband. Custodian will not make any changes to errors over three years old.

Thoughts on how this situation can be remedied and comply with the IRS?

Thank you, an advance for your comments.

Betsey