with Planner1.Header do 
begin 
  Captions.Clear; GroupCaptions.Clear; 
  Captions.Add(''); // take first sidebar header section into account 
  Captions.Add('A1'); 
  Captions.Add('A2'); 
  Captions.Add('A3'); 
  GroupCaptions.Add('Group A'); 
  Captions.Add('B1'); 
  Captions.Add('B2'); 
  Captions.Add('B3'); 
  GroupCaptions.Add('Group B'); 
end;

var 
  i: Integer; 
begin 
  with planner1.Header do
  begin 
    CustomGroups.Clear; 
    with CustomGroups.Add do 
    begin 
      Caption := 'Group 1'; 
      Span := 2; 
    end; 
    with CustomGroups.Add do 
    begin 
      Caption := 'Group 2'; 
      Span := 3; 
    end; 
    with CustomGroups.Add do 
    begin 
      Caption := 'Group 3'; 
      Span := 1; 
    end;

    Captions.Clear; 
    Captions.Add(''); 
    for i := 1 to 6 do 
      Captions.Add('Col '+inttostr(i)); 
    end; 
end;