Sam's comment above is correct if you are using Ask a Nomad through the website (http://answers.worldnomads.com/). If you're using it via the iPad app, we haven't yet created the ability to add a comment. In this case, most people keep the thread of conversation going by just adding on another answer. Alternatively, many people will let you contact them via their Profile.
Hope this helps,
Christy, Community Manager, WorldNomads.com about 6 years ago