If you want to send a post to multiple Teams groups in one go:
In one of the groups start a new conversation
Click on the edit/format icon
Select Post in multiple channels
Click Select Channels
Tick the ones you want to post to & click Update
Type in the post & send as normalTo post in multiple Teams channels at once:
Go to one of the teams
Click ‘Start a Post’
Click the
iconChange the option for ‘Post in’ to ‘Multiple Channels’
Click the
icon next to the name of the team you are currently in to add another channel
Once you have titled the post click ‘Post’