var
  p1,p2:TSeriesMarkPosition;
begin
  p1:=TSeriesMarkPosition.Create;
  p2:=Series1.marks.Positions.Position[0];
  if assigned(p2) then
    p1.Assign(p2);
  p1.Width:=p1.Width 10;
  Series1.Marks.Positions.Add(p1);
  p1.Free;
end;