Quote Originally Posted by 'dardack',index.php?page=Thread&postID=105870#post 105870
There is an event in the API AUTOFOLLOW_END. So when your addon loads make sure you run <frame name>:RegisterEvent("AUTOFOLLOW_END");, than in your event function you can check (i would check that you aren't in combat first because you stop following if you attack something a lot of times, and you don't want the spam, or maybe you do), combat is also an event PLAYER_ENTER_COMBAT (or LEAVE, dont' forget to check for both, just like follow follows other is BEGIN). Anyways in the event function if (not in combat and autofollow_end) then sendchatmessage("<name> has stopped following you.","WHISPER","COMMOND",<name of main>;
Word of warning: I found that "AUTOFOLLOW_END" was somewhat unreliable for some reason. I wrote a mod that used that event, and occasionally I would find a slave not following and had never received any notification. My best guess is that there is some other event that occurs, which also implies AUTOFOLLOW_END, so it doesn't post that event, but I was never able to narrow it down further.

Zanthor's suggestion has some merit too.

What I wound up doing is checking distances, and if any of my slaves were beyond a certain distance, it would flash an annoying message. I had it so it could be toggled, in case you had one off training or something. This worked really well overall.