To add members:
Open the Conversation.
In the Add Members dialog, select the people or groups you want to add.
By default, you see Recommendations.
To view a list of your contacts, tap More, then select the list you want to see.
To view a list of your groups, tap More, then select the list you want to see.
Alternatively, search for a person or group to add.
To view the list of people and groups you've selected, tap > next to <Number> selected.
Note: People outside your company have a special avatar () and their names are in purple text. If you add an outside user to a Conversation, a banner stating "This Conversation is visible to outside users." appears at the top of the Conversation and any associated message dialogs.
Tap outside the Members dialog box to close it.
To remove members: