How to Configure Optional Signature Fields

{
  "ESignType": {
    "Type": "Docusign",
    "DocusignTabs": [
      {
        "FieldName": "1own.38002.1.Sign",
        "Optional": true
      },
      {
        "FieldName": "1own.5.1.Sign",
        "Optional": true
      }
    ]
  }
}

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Header>
    <AuthenticationHeader xmlns="https://websvcs.quikforms.com/quikformsenginews/">
      <CustomerID>xxxx</CustomerID>
      <UserName>xxxx</UserName>
      <Password>xxxx</Password>
    </AuthenticationHeader>
  </soap:Header>
  <soap:Body>
    <Execute xmlns="https://websvcs.quikforms.com/quikformsenginews/">
		<QFESettings>
	        <ESignType xsi:type="ESignTypeDocusign">
	            <DocusignTabs>
	            	<DocusignTab>
	            		<FieldName>1own.38002.1.Sign</FieldName>
	            		<Optional>true</Optional>
	            	</DocusignTab>
	            	<DocusignTab>
	            		<FieldName>1own.5.1.Sign</FieldName>
	            		<Optional>true</Optional>
	            	</DocusignTab>
	            </DocusignTabs>
	        </ESignType>
       </QFESettings>
    </Execute>
  </soap:Body>
</soap:Envelope>

var objQFE = new QuikFormsEngine.QuikFormsEngine();
/*some QFE configuration*/

var docusign = new ESignTypeDocusign();
docusign.DocusignTabs = new List<DocusignTab> {
	new DocusignTab {
		FieldName = "1own.38002.1.Sign",
		Optional = true
	},
	new DocusignTab {
		FieldName = "1own.5.1.Sign",
		Optional = true
	}
};

/*other docusign configuration*/
objQFE.SetESignType(docusign);