Ironically, this whole topic of tracking connected topics or consolidating into topics is applying here. There have been a whole series of topics about this single issue of how split-topics are not adequately displayed. To tie the history together, here’s an older topic that really is the same (could be combined): Feature proposal: action post on split topic
On the instance I’m involved with, someone even went so far as to suggest using staff-notice because they felt an in-line mention wasn’t even adequate enough. Since the move is made by a moderator, it’s essential that the users understand what happened to their post. I think staff-notice is overkill, but something at the top (where it would be if a user just replied-as-linked-topic) really makes sense. No indication at all at the top can be really awkward since the post is often not written in a topic-opening style.