public sealed class LinkChartFeatureLayer : CompositeFeatureLayer, ArcGIS.Desktop.Core.IMetadataInfo, IDisplayTable, ILayerContainer, IMetadataSource, ITableDefinitionQueries, System.ComponentModel.INotifyPropertyChanged  

{
  var kg_layer = map.GetLayersAsFlattenedList().OfType<KnowledgeGraphLayer>().FirstOrDefault();
  if (kg_layer == null)
    return;

  if (map.MapType == MapType.LinkChart)
  {
    // if map is of MapType.LinkChart then the first level
    // children of the kg_layer are of type LinkChartFeatureLayer
    var childLayers = kg_layer.Layers;
    foreach (var childLayer in childLayers)
    {
      if (childLayer is LinkChartFeatureLayer lcFeatureLayer)
      {
        var isEntity = lcFeatureLayer.IsEntity;
        var isRel = lcFeatureLayer.IsRelationship;

        // TODO - continue processing
      }
    }
  }
  else if (map.MapType == MapType.Map)
  {
    // if map is of MapType.Map then the children of the
    // kg_layer are the standard Featurelayer and StandAloneTable
    var chidlren = kg_layer.GetMapMembersAsFlattenedList();
    foreach (var child in chidlren)
    {
      if (child is FeatureLayer fl)
      {
        // TODO - process the feature layer
      }
      else if (child is StandaloneTable st)
      {
        // TODO - process the standalone table
      }
    }
  }
}