I have been able to remove the unwanted header values from the rows (0-15) in the tree view. Unforunately those rows remain empty instead of being filled with the filtered values.

I have also found that the data() function can get both the header values AND data values.
Qt Code: 
  1. QVariant PropInspectProxyModel::data( const QModelIndex& index, int role ) const
  2. {
  3.     QModelIndex source_index = mapToSource( index );
  4.     if ( index.isValid() && !source_index.isValid() )
  5.         return QVariant();
  6.  
  7.     ///////////////////////////////////////////////////////////////////////////
  8.     // How do I know when to get the header data vs. getting the data values???
  9.  
  10.     // Get the Property header string
  11.     QVariant vHdr = sourceModel()->headerData( index.row(), Qt::Horizontal, role );
  12.  
  13.     // Get the data values
  14.     QVariant v = sourceModel()->data( source_index, role );
  15.  
  16.     return v;
  17. }
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Two unresolved issues remain:
  1. How can I get my headers to fill rows 0-9 instead of 16-25?
  2. How do I know when to get header values or data values in the data() override function?
Examples
  1. HeadersHeadersOnly..JPG
  2. DataDataOnly..JPG