[roman]

Truco "sucio" para moverse a la última fila visible del DBGrid:

type
  THackGrid = class(TDBGrid);

...

var
  Delta: LongInt;

begin
  with THackGrid(DBGrid1) do
  begin
    Delta := VisibleRowCount - Row;
    DataSource.DataSet.MoveBy(Delta);
  end;
end;

// Saludos