In keeping with the ethos of the SI project, http://paterson-associates.co.uk/property/suite-c-2-water-lane/ agency may be exercised by different entities (e.g. individuals, firms, households). A given individual can form part of multiple agents (e.g. he may belong to a firm and a household).
However, the set of agents that act in a given situation might not be common knowledge. For example, Alice may not know whether Bob and Colm have formed a coalition and constitute a collective agent.
The paper models such considerations, inspired by the classic model of incomplete information over preferences of Harsanyi.