I think the first problem could be better solved with a column that says "Include this row when displaying". You could simply have a DisplayOnsite column that's

I think the first problem could be better solved with a column that says "Include this row when displaying". You could simply have a DisplayOnsite column that's a bool. If true, display. In your view/proc/method/whatever (in SQL), just eliminate any rows WHERE DisplayOnsite=0. One thing pops to mind: Do you ever want to change the order of the threaded comments? For example, if you are having a Q&A forum, do you want people to be able to "Mark as Correct Answer" and then you sort by the most votes for correct answer first? That would affect the hierarchy.