Microsoft Teams is now allowing you to add a new tab to a Yammer group.
To do so, just hit the + (plus) sign to add a new tab and search for Yammer
Then ensure the ‘Add to a Team’ option is set to Yes (default) – if set to No, you will not be able to install it – and click Install
Then define which Yammer content type (Yammer Group or Yammer Topic) to push in your Teams as well as the Yammer Group – there is no drop down or prefilling, you need to search for the group
NOTE this page may be a little bit longer to load
This is it, the Yammer group is now added to your Teams – you can at anytime use the View in Yammer button (top right) to go to Yammer
And I have posted a message from Teams to the Yammer group, you can see it show ‘from Teams Desktop app’