From STDs Doc 24. Does this help?
If a test is conducted without a fully constituted crew, each crew member is expected to demonstrate competency in their normal operating seat. Exceptions to this may be acceptable, for example: two training captains, a captain not normally acting as PF when operating in the RHS. Two first officers shall complete all handling exercises and scenario based assessments in their normal operating seat. Exception can be made for scenario based assessments, but as there are only limited scenarios where two first officers could find themselves operating together, this should not be routinely scheduled.
rgds