Updating the Envelope with new documents and sending the Envelope does not reflect the updated documents in Docusign

I have installed Docusign App Launcher in my Salesforce developer org. I am using the generate_and_convert REST API to generate the documents and then I am sending these documents using sendEnvelope method of EnvelopeService ApexToolkit. 
I have the requirement of getting a list of documents as and when it comes and then updating them onto an Envelope and finally send the Envelope. For this I have created an empty envelope with a recipient and sent the Envelope with Boolean false.

Contact myContact = [SELECT Id,FirstName,LastName,Email,Phone FROM Contact WHERE Name = 'Test Contact']; 
dfsle.Envelope myEnvelope = dfsle.EnvelopeService.getEmptyEnvelope(new dfsle.Entity('mysourceId'))
    .withRecipients(new List<dfsle.Recipient> {
        dfsle.Recipient.fromSource(
            myContact.FirstName + ' ' + myContact.LastName,
            myContact.Email,
            myContact.Phone,
            'Signer 1',
            new dfsle.Entity(myContact.Id))
    });
myEnvelope = dfsle.EnvelopeService.sendEnvelope(myEnvelope, false);

Once this Envelope is saved in Docusign...I try updating the Envelope with my documents.

List<dfsle.Document> documentList = dfsle.DocumentService.getDocuments(ContentVersion.getSObjectType(), new Set<Id>{myDocId});
system.debug(myEnvelope1.docuSignId);
myEnvelope = dfsle.EnvelopeService.updateEnvelope(myEnvelope)
                .withDocuments(documentList);

Once I finish with this I do sendEnvelope again. However I do not see the documents in Docusign. 
Is this is the way how it should be done. or is there any other way that this can be achieved. 
Thanks for your reply