Phone Authentication with editable phone number and country code with PropertyMetadata ?

Hello,

We are DocuSign C# SDK.

We are configuring recipient identity verification through phone authentication with IdentityVerification < Signers < Recipient < EnvelopeDefinition 

We have 

IdentityVerification = new RecipientIdentityVerification
{
                WorkflowId = _signatureSettings.PhoneAuthenticationWorkflowId,
                InputOptions = new List<RecipientIdentityInputOption>
                {
                    new RecipientIdentityInputOption
                    {
                        Name = "phone_number_list",
                        ValueType = "PhoneNumberList",
                        PhoneNumberList = new List<RecipientIdentityPhoneNumber>
                        {
                            new RecipientIdentityPhoneNumber
                            {
                                Number = signer.Phone.Number,
                                CountryCode = signer.Phone.CountryCode,
                            }
                        }
                    }
                }
}

How can we permit the signer to provide an other phone number when they are in the phone authentication process ? 

I see that in RecipientIdentityPhoneNumber there is “NumberMetadata” & “CountryCodeMetadata” with those descriptions : ”Metadata that indicates if the `number` property is editable.” & “Metadata that indicates if the `countryCode` property is editable.”

The expected type is “PropertyMetadata” with List<string> Options & string Rights.

How can we use it so that signers can edit their phone number when authenticating?

Thank you