Use subgroups to organize your group into smaller, specific groups. You can hold conversations just for subgroup members. See Adding a subgroup in Wiggio to a conversation [1] for more information.
Note To remove users from the These members are in the subgroup list, select the members you want to remove, then click Add or Remove Members.
Links:
[1] http://staging.docs.d2l/en/adding-subgroup-to-conversation-in-wiggio
[2] http://staging.docs.d2l/en/taxonomy/term/3