After all, an interesting feature. Maybe enforced by some bylaw in some type of "Facebook" web, just to limit bullying and other undesired or unsolicited type of communication. If this forum would run properly, collabs should reply to the originator only. Unfortunately, replying to the originator does not plug next to the original post, not always as actually. Personally, I don't care because visit(s) worth collaboration deserve a separate work sheet or linked to a related work sheet already in the forum... that's what I do since my first membership. That PTC had considered Mathcad as a chat box, is their business ... not yours, not mine.