I have the exact same situation at hand. For example: a colleague announces an event and asks the people to reply to the post to register for the event. If you want everyone to receive the invitation, everyone will get the replies too. It would be neat if you could make it so you don't receive e-mails from replies on a thread, par from the creator of the thread (or is there a way to do this?).
Our current work-around is sending the invitation with a Google Form and make them register there, would be a lot nicer if they could reply on the forum (and if possible: hide the replies too?).