Try Sharing History and Modify Sharing
Once you have shared an Group, then you will get sharing history () icon in the Group listing page next to the Group you have shared.
1. On clicking the sharing history () icon, following screen appears:
2. In the above screen, the person(s) with whom the Group is shared will be listed.
1. On clicking the cog wheel () in the Action column, lets the user update the sharing privileges using the following screen:
2. Now, clicking on any of the desired option, the privilege can be updated.