Feb 25 2018 05:17 PM
Feb 26 2018 07:20 PMSolution
Nov 30 2018 04:27 AM
Dec 04 2018 01:49 PM
I don't believe you can turn an existing group into an external group. But, you can create a new external group, use the "Share" link to get comments from an existing group into the new external group, and then archive the old group.
It ain't easy, but it can work.