GJ User batch process needs Copy/Move

Hi,
I have a group with users.
Then they create a subgroup (but all users of the subgroup have to stay users of the parent group.
It seems, I can only move users from the group to the subgroup.
But there should be a possibility to copy users grom one group to another! I think, it would be a big help.

I remember me, that notifications for the group users don't go to the users of the subgroup! So it needs the users of the subgroup have to be in both groups (the parent and the subgroup)

You can already mass move users. Navigate to GJ > Users, check a bunch of checkboxes, then under batch processing select a group you want them to belong to. Users don't have to exist in the parent and child at same time (let me join at their own leisure, perhaps they don't want child group notifications?). I've no plans to add a copy feature for Users, sorry.