I don't know of any prohibition against appointing a Deputy Chair for the SSET. While section 1.4.4.1 of the DoD Source Selection Procedures states: "The SSEB is comprised of a Chairperson and Evaluators," I don't think it necessarily precludes adding a Deputy to the team. However, it may raise the question of why the "inexperienced" individual is made the Chair instead of the Deputy. In any case, I would make sure that the duties of the Deputy are spelled out in the source selection plan.