1. Apply multiple templates to a single envelope.
2. Replace the documents on your saved DocuSign server templates when creating the envelope, but still have the server template apply all the tabs to the recipients in your envelope.
3. Write values at run time into the text tabs and other data fields on the server template.
4. Add additional tabs at run time.
5. Transform PDF fields into DocuSign tabs and assign them to recipients.

{
  "compositeTemplates": [
    {
      "compositeTemplateId": "1",
      "document": {
        "documentBase64": "PDF Bytes",
        "documentId": "1",
        "fileExtension": "pdf",
        "name": "Statement of Work"
      },
      "inlineTemplates": [
        {
          "recipients": {
            "signers": [
              {
                "email": "g...test@example.com",
                "name": "Geoff Test",
                "recipientId": "1",
                "roleName": "Customer",
                "routingOrder": "1",
                "tabs": {
                  "textTabs": [
                    {
                      "tabLabel": "HourlyRate",
                      "value": "$180.00",
                      "locked": "true"
                    }
                  ]
                }
              }
            ]
          },
          "sequence": "2"
        }
      ],
      "serverTemplates": [
        {
          "sequence": "1",
          "templateId": "57fd4752-xxxx-xxxx-xxxx-ecbfc7a43bef"
        }
      ]
    }
  ],
  "emailSubject": "CompositeTemplate Example",
  "status": "sent"
}
                                          

public static string CompositeTemplateExample()
{
    // Instantiate ApiClient and configure authentication. Method not not shown.
    string accountId = GetAPIandAuthenticate();     
    EnvelopesApi api = new EnvelopesApi(Configuration.Default);
  
    // Create a list of composite templates
    List<CompositeTemplate> CompoTemplateList = new List<CompositeTemplate>();
    // Create one Composite Templates
    CompositeTemplate compoTemplate = new CompositeTemplate();
    // Create a document
    var documents = new List<Document>();
    byte[] fileBytes = null;
    Document doc = new Document();
 
    fileBytes = File.ReadAllBytes(@"C:\temp\SOW1.pdf");
    doc.Name = "Statement of Work";
 
    doc.DocumentBase64 = System.Convert.ToBase64String(fileBytes);
    doc.DocumentId = "1";
    doc.FileExtension = "pdf";
    // Add to Composite template
    compoTemplate.Document = doc;
    // Create Envelope recipients, including them in the first template
    List<Signer> signers = new List<Signer>();
    // Create the tab for hourly rate
    Tabs tabs = new Tabs();
    Text textBox = new Text();
    textBox.TabLabel = "HourlyRate";
    textBox.Value = "$180.00";
    textBox.Locked = "true";
    tabs.TextTabs = new List<Text>();
    tabs.TextTabs.Add(textBox);
    //Create the signer and add the tabs to pick up the HourlyRate
    Signer newRecipient = new Signer
    {
        Email = "g...test@example.com",
        Name = "Geoff Test",
        RecipientId = "1",
        RoleName = "Customer",
        RoutingOrder = "1",
        Tabs = tabs,
    };
    signers.Add(newRecipient);
    //Create first list for InlineTemplates
    List<InlineTemplate> inlineTemplateList = new List<InlineTemplate>();
    InlineTemplate inlineTemplate = new InlineTemplate();
    inlineTemplate.Sequence = "2";
    inlineTemplate.Recipients = new Recipients();
    inlineTemplate.Recipients.Signers = signers;
    // Add it to the inlineTemplatesList
       inlineTemplateList.Add(inlineTemplate);            
    // Create the reference to the template housed on your DocuSign account
    ServerTemplate serverTemplate = new ServerTemplate()
    {
        Sequence = "1",
        TemplateId = "ce839909-xxxx-xxxx-xxxx-a05dbd8c7217" // Statement of Work
    };            
    List<ServerTemplate> serverTemplateList = new List<ServerTemplate>();
    // Add it to the templates List
    serverTemplateList.Add(serverTemplate);    
    // Create the composite template, add the server / inline template lists.
    compoTemplate.CompositeTemplateId = "1";
    compoTemplate.ServerTemplates = serverTemplateList;
    compoTemplate.InlineTemplates = inlineTemplateList;
    // Take the Composite Template list, add both
    List<CompositeTemplate> compositList = new List<CompositeTemplate>();
    compositList.Add(compoTemplate);
    // Create the definition for the envelope
    EnvelopeDefinition envDefinition = new EnvelopeDefinition();
    //Add the Composite Template list
    envDefinition.CompositeTemplates = compositList;
    envDefinition.EmailSubject = "CompositeTemplate Example";
    envDefinition.Status = "sent";
    EnvelopesApi.CreateEnvelopeOptions options = null; //No query parameters
    // Create the envelope
    EnvelopeSummary Response = api.CreateEnvelope(accountId, envDefinition, options);
    string envelopeId = Response.EnvelopeId;
    Console.WriteLine(envelopeId);
    Console.ReadLine();
    return envelopeId;
}