When inside of a group you have the option to select multiple people and add them to another group. There are times when you will want to add them to another group for follow up or next step groups.
To multi select members, go inside the Members tab of the group.
From there you can click on the area around the name and it will select it and turn the background from grey to white and the bulk actions will show in blue.
Then select the Add to Another group option at the top to add to this new group. This will not remove them from this group but add them to an additional group.