Copy Users from one 'Secondary UserGroup' to another?

[s.blair]

Is there a way to copy all the users from one Secondary or 'Additional' UserGroup to another?

We frequently create new Private Forums for Beta Software Releases. Each new Release gets a new Private Forum and hence a new Secondary UserGroup.

As the members change only slightly from one group to another we need a way to easily either mass edit secondary usergroup membership or to copy the members from one usergroup into another so we can modify from there.

Any ideas?

Thanks.
Scott