When we create a new user, one of the things that we often may do to get a quick start is to "Add groups from another user" effectively copying the group membership of the other user.
I was asked to create 2 new groups with around 150 members each which were copies of two existing groups. These groups currently will have the same members as some other groups but will need to be decoupled moving forward as those teams diverge. Being a dev ops kind of guy, I can think of a number of ways to do this, but in my current environment there are many Business Admins who are discouraged from using shell utilities / ldap browsers or are uncomfortable in those environments. That is when I thought, there really should be an "Add members from another group" option during creation of a new group. Even a way to select and copy and paste members from within those interfaces would work but unlike the team page there is no copy and paste option from within the participant admin / group interface.