Nope. In Mastodon, every message has its own scope completely independent of any other message associated with the thread. There is no 'reply to all'. Your replies "usually" go to your own followers and anybody  you mention, which "usually" includes the author of the post you are replying to - but never to their followers or the original audience. There is no such thing as a conversation which is seen only by the audience of that conversation. This is why I've been working so hard on conversation containers, which fixes this situation.