There doesn't seem to be a function to forward conversations. Yet, this function is used frequently by our members. (still on vbulletin ATM) Adding new participants to a conversation does not cater to the same purpose, because that will show the sender that the message is being forwarded. In many cases the forwarder intends to discuss the forwarded message with a third party without the sender to be included in the discussion. Forwarding messages is pretty standard functionality in email and forum software, so it should be implemented in XF. Please add a conversation forwarding function to XenForo. It should be possible to forward either a message or a whole conversation.