Terminating Plan with Missing Signed Amendments

[WolverineBenefits]

A client is terminating an individually designed defined benefit pension plan. We are unable to find signed copies of a 2017 amendment (or corporate resolutions reflecting the adoption of the amendment) related to the addition of optional forms of distribution (i.e, not an amendment to update the plan for legal changes). The Plan has been operated in compliance with the amendment since it was "adopted."

We are planning to file a Form 5310 for the termination. Any thoughts on how the Service might handle the missing signature? Even if we wanted to file a VCP request, it would not be resolved in time to file the Form 5310. 

Thanks in advance.