As in the title. Has to do mainly with companions as they are kind of useless at the moment. Since the system is already in place for players, it should be straightforward to make it work with followers.
If you are in the same party, then everyone gets a share of the XP. In other words, threat them in the same way as if they are another player. This of course is open for discussion. While we are at it, the highlight should be green for followers that belong to players in your party.
Highlight yes, but I say if a player wants three followers he should divide his own XP. They're NPCs, not players.