Reply button in comment section

How can I add Reply button in the comment section?

Hello! Do you mean you want to include the button in the current Taiga (Taiga 6)? Or do you like us to consider it in the next version of Taiga (Taiga Next)?
For Taiga Next, we will take it into account for sure. However, for Taiga 6, it is pretty challenging to add it.
I hope I have answered your question.