Containing Group (Parent)

This is the Group that contains your selected Part, if one exists. For example, Group Omega contains Node F, but no Group contains Node A.  Although Phi contains Omega, and Omega contains F, clicking F does not highlight Phi, as it is not an immediate parent of F.  In code, this highlighting is done as follows:

 if (myDiagram.SelectedPart.ContainingSubGraph != null) {
  ((NavModelNodeData)myDiagram.SelectedPart.ContainingSubGraph.Data).Highlight = 1;
}