In a recent working paper, Jonathan Newton gives a fixed point solution concept that incorporates http://rg-onlinesolutions.co.uk/does-rexavar-really-work.pdf： collective agency under incomplete information.
In keeping with the ethos of the SI project, click 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.