Add People to a Group Chat in Slack and Teams Without Oversharing History
A quick direct message grows into a project conversation, and now someone else needs to join. Before adding them, check what they need to see. Slack and Teams both document history choices, but they do not describe the same behavior when a one-to-one conversation becomes a group.
Miles Crawford
Slack group DMs: small conversations, optional names
Slack describes direct messages as conversations outside channels. They can be one-to-one or include up to nine people. To start a new DM, use the plus button in the desktop sidebar or the compose button on mobile. The DMs area also has a new-message control.
You can give a group DM a name on desktop: open it, hover over the members' names at the top, click the pencil icon, enter the name and select Save. Our suggestion is to use the task or project as the name. Several chats with almost the same participants are easier to distinguish when the names explain what each conversation is for.
Add someone in Slack: review the history choice
On desktop, open the DM, click the names in the conversation header and select Add people. Type and select the person, then click Next. Choose an option under Include conversation history. Click Done, then Confirm when you are ready.
On mobile, tap the names at the top of the DM, then Add. Select the people, tap Next, choose an option for Include conversation history and tap Preview. Finish with Done when the selection is right.
Slack says the selected conversation history moves to a new group DM containing the new members. Messages and files are visible to them based on the history you choose. Slack also posts automatic notifications to the relevant conversations. This is not a silent change to an unchanged audience.
Our recommendation: read the selected range before confirming. A conversation can mix useful project context with a side comment or file that was never meant for the new person. If the range is unsuitable, start a fresh conversation and write a short factual recap instead of sharing everything for convenience.
Teams: name the group when you start it
On desktop, select New message at the top of your chats and channels list. Select the down arrow at the far right of To to reveal Group name. Enter the name and add the people in To. Compose and send the opening message to begin the conversation.
On mobile, tap Chat, then New message. Enter the people in To, type the message and send it. To name the group, tap the participant names at the top, choose Group chat name, enter the name and select Save.
Microsoft documents up to 250 people in a Teams group chat. That is a capacity limit, not our recommended audience size. For a small decision, invite the people who need to take part. If the conversation becomes ongoing team knowledge, reconsider whether a channel is the better home.
Teams history works differently for an existing group
To add someone to a Teams group chat on desktop, select View and add participants, then Add people. Enter the names. For an existing group chat, choose how much chat history to include, then select Add.
On mobile, open the group chat, tap the participant names at the top, then Add people. Enter the new people, choose how much history to include and tap Done.
Microsoft explicitly says you can include history when adding someone to an existing group chat, not to a one-on-one chat. Do not carry Slack's history behavior across to Teams. Microsoft also says that if someone leaves a group, their messages remain in its chat history. Leaving is not the same as erasing what they wrote.
To check the audience, use View and add participants at the top right on desktop, or tap the participant names on mobile. Our suggestion is to check this list before posting a sensitive detail, especially when several similarly named groups exist.
Give the new person a useful first message
Our suggested opening is: "Adding the onboarding lead to decide the handoff date. The current proposal is Thursday; we need confirmation of the support owner before we commit." Replace the sample role, date and decision with facts from your own situation.
A short recap should state why the person is here, what is already decided and what you need from them. A check reaction can acknowledge that recap, but should not stand in for an answer to an unresolved question. If someone must approve the handoff, ask for that approval in words.
If Slack's nine-person DM limit is too small, its help suggests moving the group DM to a private channel. Treat a move or audience expansion as its own choice. Neither a new group name nor a friendly welcome message replaces checking who can see the conversation and which history was included.
Sources
Checked October 27, 2026. Product steps and history behavior come from official help; audience checks and message examples are our recommendations.