iMessages - can one disable 'join/leave' messages in group chats? Does anyone know where you can disable the join/leave messages in group chats in iMessages? In low-traffic chats it's utterly annoying to have scrollbacks full of 'xxx joined the chat.'/'yyy left the chat.'

Thanks.
As far as I know this isn't possible, I checked the iPhone, iPad and Mac version but this setting is nowhere to be found.
As for changing it through terminal or fiddling with program files, that will only change the setting on the mac.