If you are part of a group, you can add someone by searching, or by mentioning them.  

Note: If you want to add people to a group you're creating, see the article Create a Group.

Add someone via a Mention

you can mention the person (i.e., “@[person’s name]) to automatically send them an invite to join the group.

Add someone by searching

1. Navigate to the group you want to change.
2. Click the Group Details button to open the Group Details pane.

3. Click Add. A Search pane appears.  

4. Search for each person you want to add by name, number, or extension. Click on their name to add them to your list of invitees.

5. Click Add. Each person you selected is sent an invite to join the group via a chat message.

Important: Sharing Group Chat History

When new members are added to a group, you can choose to share the group chat history with them, or you can start a new conversation.

Click Got It, Add Members to add a new member to the existing group. Click Start a New Conversation to create a new group which contains the new member and all previous members.