In Revit, a Group has both an Instance Workset and Type Workset. Whatever Workset is active when the Group is created is assigned as both the Instance and Type Workset. The Individual Elements in the Group inherit the Groups Instance Workset. This holds true even if you change the Instance Workset of the Group. The Objects in the Group stay synchronized with the Group’s Instance Workset. Confused? Me too. I tried to draw a picture.
So, to sum up:
1. Groups have both Instance and Type Worksets parameters
2. The Workset is assigned based on the Active Workset at the time the Group is created
3. Objects within the Group follow the Instance Workset
I can’t possibly imagine a scenario when you would want to have the Instance and Type Workset values to be different. The best workflow I think is to maintain a Workset for Groups and make sure all your groups stay on that Workset.
One last note, when you Ungroup the Group, the Individual Elements in that Group keep the Workset they were assigned while part of the Group. So, when Ungrouping, you will need to be sure to move those Elements off of the Group’s Workset and onto an appropriate Workset.