Read a topic about Nested Commenting in K2. Answer was that it is not supported in current K2.

My question: Are there any Extensions available and compatable with K2 for commenting on articles and replying to comments (nested)?

Many Thanks

Hello Will,

The answer was correct,
Nested commenting is not supported.

You can use a commenting service like Disqus or Facebook comments. There are plenty of extensions which will integrate these services with K2.