C# Custom Dockable window: grouping them together

I’m adding in some custom windows for our clients. I want to group my dock windows together on load. The end result would look like they are tabbed (from the bottom).

I have the following code to my button (x 3 ):

ESRI.ArcGIS.Framework.IDockableWindow aaView;
...
if (aaView == null)
            {
                //Get dockable window.
                UID dockWinID = new UIDClass();
                dockWinID.Value = "myView";
                aaView = ArcMap.DockableWindowManager.GetDockableWindow(dockWinID);


                if (aaView == null)
                {
                    ErrorBox.DoModal("Launchmyview Error", "", "", "", 1);
                    return;
                }
            }
            aaView.Show(!aaView.IsVisible());

I have the following in the esriaddinx(x3):

 <DockableWindow id="MyView" class="CustomEvents.ImageMetaData+AddinImpl" caption="Raster Metadata">
          <InitialPlacement height="300" width="300" state="unpinned" position="group" neighbor="{E1F29C6D4E6B11D2AE2C080009EC732A}" />
        </DockableWindow>

I know that I can move the windows over eachother manually once the UI is open, but I want to group them programmtically.