Within Teamwork Chat, you can choose to automatically add new users to a particular channel by default.

To make an existing conversation/channel into a default channel, click the options button (three dots) in the top right of the channel and select Edit channel.

Image Placeholder

In a conversation, you will need to convert it to a channel first by clicking Convert to channel.

Image Placeholder

In the create/edit modal, select the Automatically add new users to this channel option.

Image Placeholder

Once selected, every new member will be added to this channel as default.

Note: Only a public channel can be set as a default channel. 

For more information, see: Creating a Conversation or Channel