code: def new_member(group_id):
      
      group = Group.query.get_or_404(group_id)
  
      if group.can_invite_others(current_user):
          form = NewMemberForm()
  
          if form.validate_on_submit():
              emails = filter(None, form.data['emails'].splitlines())
              group.invite_by_emails(emails)
              flash(_('Requests sent!'), 'success')
              return redirect(url_for('.members', group_id=group.id))
  
          return render_template(
              "invenio_groups/new_member.html",
              group=group,
              form=form
          )
  
      flash(
          _(
              'You cannot invite users or yourself (i.e. join) to the group '
              '%(group_name)s',
              group_name=group.name
          ),
          'error'
      )
      return redirect(url_for('.index'))
docs: Add (invite) new member.