Groupings: Strangely Related Events
A "grouping" is a number of strange accounts that show a distinct similarity, but are not related by their place of occurrence -- which would make the group a "haunting" or "hotspot" -- nor are they related in their time of occurence -- which would make the group a "flap".
These groupings are not large enough to become full topics unto themselves, but are distinct enough that they can be pointed out as their own unique thing. Generally the way events in groupings are related to one another is that either they all share a common origin point, or they all share a similarity in strange behavior or occurrence... but the individual events themselves are spread across various places and times.