A figurative relation may involve a cause and its result, a place and its occupants, or a carrier and its load. In some examples the relation is a recognizable contextual association rather than strict necessary entailment.
Not every relation must be an unbreakable logical implication. Any particular waterskin can be transported by different carriers, and a meeting place can be occupied by different people. Yet established association and contextual wording may guide the listener successfully.
The requirement is a legitimate pathway of semantic transfer, not the claim that the two things must be inseparable in all possible circumstances.