A, B and C where entity C is created by entity B on behalf of entity A.C I know the instance of both B and ABs for each A (though the Bs can be used by many As and there are potentially millions of Cs, which belong to only one BCs for A and sometimes with all Cs created by a particular B on behalf of A.A->B->C A->CA->C of course, but given the low cardinality of B, is A->C overkill and I can just find all C by iterating B for A without too much cost.