Confluence - Multiple Slack teams
Setup Slack app. If you have already setup, So skip it
Setup multiple Slack teams for a Confluence Space
Navigate to Space tool in given Space
Click on Slack tab
Click on "Connect" button
Choose your wish slack team at right top corner . My sample is "Slack Connector"
Click on "Authorize" button at bottom then you able connect "Slack connector" team to current Confluence Space
Click on "Connect" button , then choose other Slack team at top right dropdown
Now you are able to connect multiple Slack teams in to your current workspace.
If you need to setup for global configuration , see at Confluence slack global notification