How do I privately reply to one individual in a group message in the Inbox?
Even when you are part of a group conversation, you can privately respond to another individual.
Open Inbox

In Global Navigation, click the Inbox link.
Select Conversation

Select the conversation.
Locate Message
Locate the individual you want to send a private message to. Hover your mouse under the timestamp until you see the Reply icon.
Compose Message

Type a message in the message field [1]. When you are finished, click the Send button [2].
The message will send to the person in the To field and not to everyone else. If you want to reply to everyone, click the settings icon and select reply-all. Or use the reply-all button in the toolbar.