Can I import replies to posts using RSS Polling and how do I set it up?
RSS scrolling can create new topics.
What is the ‘reply’ for this topic. How to publish RSS rolling?
The RSS plugin creates new topics. The reply is for your community to reply to the topic.
I am not sure about it pulling replies.
There is a plugin that may help do something like that called Activity pub. From my understanding it might be possible to use it say for example between 2 Discourse forums to have a topic that spans between them. It uses Mastoden as a go between. And you can also respond in Mastoden. Forgive me though my understanding might not be entirely correct.
Best to read this very this topic on the Activity pub plugin and ask questions for better clarity