Add members to more groups - without further registration

I have asked in other groups, but I'm refered to this.

Is it possible for the administrator to:
*Search among registered members by their Interests (advanced search of metadata),
*Grap these member (UIs) all together with their profiles and
*Add them to a newly registered Group?

If so it'll need Grapping the users identifiers from metadata and add these to the Group UI OR
       it'll be possible to upload a list of well-known members to the Group-ID ( no registration).

The point is that every new required registration loose members and the users have already said yes expecting to be directed to sub-groups.

If not - any idea forward or known plugins that can do this?