IElement FindElement( 
   string elementName,
   bool recurse
)

//Create a group with a list of elements at the root level of the contents pane.

//Find an existing elements
//container is IElementContainer - GroupLayer or Layout
var elem1 = container.FindElement("Polygon 1");
var elem2 = container.FindElement("Bezier Text");
var elem3 = container.FindElement("Cloud Shape 2");

//Construct a list and add the elements
var elmList = new List<Element>
{
  elem1,
  elem2,
  elem3
};

//Perform on the worker thread
await QueuedTask.Run(() =>
{
  //At 2.x - GroupElement groupWithListOfElementsAtRoot =
  //             LayoutElementFactory.Instance.CreateGroupElement(layout, elmList);
  //groupWithListOfElementsAtRoot.SetName("Group with list of elements at root");
  //
  GroupElement groupWithListOfElementsAtRoot =
          ElementFactory.Instance.CreateGroupElement(
                   container, elmList, "Group with list of elements at root");
});

// *** or ***

//Create a group using a list of element names at the root level of the contents pane.

//List of element names
var elmNameList = new[] { "Para Text1", "Line 3" };

//Perform on the worker thread
await QueuedTask.Run(() =>
{
  //At 2.x - GroupElement groupWithListOfElementNamesAtRoot =
  //   LayoutElementFactory.Instance.CreateGroupElement(layout, elmNameList);
  //         groupWithListOfElementNamesAtRoot.SetName(
  //                  "Group with list of element names at root");

  //At 3.x, use the names to find the relevant elements first
  //container is IElementContainer - GroupLayer or Layout
  var elems = container.FindElements(elmNameList);
  GroupElement groupWithListOfElementNamesAtRoot =
      ElementFactory.Instance.CreateGroupElement(
           container, elems, "Group with list of element names at root");
});