1. Go to the MANAGE > Groups.

  1. Open the group you wish to change.
  2. If you have not set the admissibility of being a member of multiple subgroups yet:
    1. Click on settings to the right of heading Administration.

    1. Click on edit in the section Members rights.

    1. Check the square box in front of Users can be members of several subgroups.
    2. Confirm by clicking save.

  1. Click +ADD after entering the group page and select Invite user.
    1. Even if the member is already part of the group, type in the member’s email address and select which subgroup you'd like to invite them to from the list.
    2. If the member is not yet part of the group, type in the user’s email address and choose the respective subgroup you'd like to invite them to from the list.
  2. Confirm by clicking INVITE.

  1. Repeat step 4 and 5 to add the member into more subgroups.


Note: Find more information on Group management in this article, please.