Originally Posted by lunarwtr
Check the "In Combat" player value during the chat log event. If between events you detect im combat is true, and withing a certain threshold you get a kill message, then count it.
Right, that's idea #2 in the original post. Some potential to credit something that wasn't actually from your group, especially in crowded areas, but I'm willing to implement it that way if it's good enough for most people.
Thanks for the feedback!