Not sure I fully understand: an item in the calendar is a little bit like an email in your inbox - it's been received, and all you can do directly with it is view it. As with material in the inbox, you can respond in some way, which will create a new item
(eg, email response or forward a calendar entry) and those new items will let you set the noreply, etc status. By the time the thing is in your calendar, it's too late to affect it. When you create the calendar entry in the first place (eg, by issuing a meeting
request), the buttons should be available, to let you mark the item as not forwardable when it lands in the recipient's calendar. In other words, if you want someone not to be able to forward a calendar entry, it needs to be marked as no-forward when it's
first created, and you can't change that setting once it's in the calendar. Does that make sense?
I do have to admit, though, that this hasn't been tested much!