Changing the Expiration Date after a Customer has signed but before we Sign

We would like to give the customer 15 days to sign the Document but then after they have signed to reset the Expiration Date to 90 days for us to counter-sign. In our business, the signature for a customer signifies that we will begin building the Fiber from our location to the customer site. The process involves site surveys and cost estimates to determine whether the price on the service provided is accurate. We have already committed to the customer that we will provide Service by having them agree to our terms of Service. The counter-signature is more of a formality than a necessary part of the contract. In my Sandbox testing, when the customer has signed, it appears that the package has been locked down and I am not able to update the Expiration date of the Package. Even though, the expiration date of the package just signifies how long the Package will be "live" on E-Signature. Is there any way around this? eslClient.ChangePackageStatusToDraft(ESignId); The remote server returned an error: (400) Bad Request. HTTP PUT on URI https://sandbox.esignlive.com/api/packages/ESIGNID. Optional details: {"messageKey":"error.validation.cannotChangePackageStatus","message":"Cannot change package status.","code":400,"name":"Validation Error"} DocumentPackage packageToUpdate = PackageBuilder.NewPackageNamed(GetPackages.Results[i].Name) .ExpiresOn(DateTime.Now.AddDays(90)) .Build(); eslClient.UpdatePackage(ESignId, packageToUpdate); Gerry