If somebody has not completed all of the pre-work in a group review session, do you still have the staff participate?

It depends on the reasons why the pre-work isn’t done. Yes, people can get busy and sometimes are not able to complete all of the pre-work before each group session, and I would allow some flexibility. However, if there is a repeat pattern with not completing the pre-work or training modules before a group review, it may need to be addressed. And yes, sometimes having them skip the group review is a consequence.