In principle you can adjust the number of lines shown in the summary text file with the option summary lines = x. If you increase that value, you start seeing some part of the reply. For elog itself  it is impossible to distinguish the reply text from the origial text, since some people use plain text like

with the reply sometimes below, sometimes above the original text. Other people use full HTML with tables (like in this forum), where it is very hard internally to distinguish between original and reply text. The easiest is not to quote the original text in replies, then you will see it always.

 Thank you very much for your answer.

Is there any way to invert the order of the original text and the reply text ?

You just start writing on top of the cited text 

.author_name {
  width:10%;
  text-align:right;
  font-size:14pt;
  background-color:#AAAAFF;
  border:1px solid #0000FF;
  border-top:1px solid white;
  border-left:1px solid white;
  padding:3px;
}

.author_value {
  width:10%;
  font-size:14pt;
  border:1px solid #308000;
  border-top:1px solid white;
  border-left:1px solid white;
  background-color:#BBCCBB;
  padding:3px;
}