To add meters to an existing group:
- Click on the group that you want to add meters to.
- Click the "+Add meters to group" button. This button is to the right of the meter icons that already exist in the group. In the image below it it towards the middle/right of the dashboard.
- This will take you to the Add Meters modal.
- check the boxes next to the meters you want to add.
- Click "Save" when you are ready.