[Loviedo]

A lo mejor te sirve algo parecido a esto:

Código Delphi [-]
procedure TForm1.Imprimedocumento1;
var
  NDRStream:  TMemoryStream;
begin
  NDRStream := TMemoryStream.Create;
  try
    RvProject1.Engine := RvNDRWriter1;
    RvProject1.open;
    while not Table1.eof do
      begin
        RvProject1.SelectReport('Detalle',true);
        RvProject1.SaveToStream(NDRStream);
        RvNDRWriter1.Stream:=NDRStream;
        RvProject1.Execute;
        RvRenderPrinter1.Render(NDRStream);
        RvProject1.SelectReport('Carta',true);
        RvProject1.SaveToStream(NDRStream);
        RvNDRWriter1.Stream:=NDRStream;
        RvProject1.Execute;
        RvRenderPrinter1.Render(NDRStream);
        Table1.next;
        Application.ProcessMessages;
      end;
    RvProject1.close;
  finally
    NDRStream.Free;
  end;
end;

Saludos.