Dear David, I think that the module not supporting group summissions is exactly the problem. I find myself in the same position of assigning the students the evaluation of group works, and I need to find ways around the limitation of workshop activity.
I usually ask the students to upload just an assignment per group, doing a manual allocation, and finally copying the received grading to the other menbers of the groups. With many students, this is going to be coumbersome and error prone.
I just don't get why the activity cannot support group submissions. BTW what do you mean by "officially support"? Is there a way of getting an "unofficial support"?
Best,
--sergio