"relatedness" or "tagging" is typically handled generically in
Wikidata
through the use of "part of" and "has part" properties.
They work terrifically well to apply some generic classification needs such
as those of the Black Lunch Table efforts.
So, an alternative to the current modeling could be...
Are they only persons ? if so, mark them as "participant of" ->
"Q28781198" Black Lunch Table
Are the topics needing some "tagging" for classification sometimes more
than persons ? if so, mark them as "part of" -> "Q28781198" Black
Lunch
Table
-Thad