procedure TForm1.SubscribeDataChange;
begin
  ClientA := TEasyUAClient.Create(nil);
  ClientEventHandlers1 := TClientEventHandlers.Create;
  ClientA.OnDataChangeNotification := ClientEventHandlers1.OnDataChangeNotification;
 
  ClientB := TEasyUAClient.Create(nil);
  ClientEventHandlers2 := TClientEventHandlers.Create;
  ClientB.OnDataChangeNotification := ClientEventHandlers2.OnDataChangeNotification;
 
  ClientC := TEasyUAClient.Create(nil);
  ClientEventHandlers3 := TClientEventHandlers.Create;
  ClientC.OnDataChangeNotification := ClientEventHandlers3.OnDataChangeNotification;
 
  ClientD := TEasyUAClient.Create(nil);
  ClientEventHandlers4 := TClientEventHandlers.Create;
  ClientD.OnDataChangeNotification := ClientEventHandlers4.OnDataChangeNotification;
 
  Try
    while (.....) do
    begin
      if (iRowNr1 <= 1000) then
      begin
        ClientA.SubscribeDataChange(...);
      end
      else if (iRowNr1 <= 2000) then
      begin
        ClientB.SubscribeDataChange(...);
      end
      else if (iRowNr1 <= 3000) then
      begin
        ClientC.SubscribeDataChange(...);
      end
      else if (iRowNr1 <= 4000) then
      begin
        ClientD.SubscribeDataChange(...);
      end;
      iRowNr1:= iRowNr1 + 1;
    end;
  Except
 
  End;
end;