Parent/child domain - delegating control to users

Hi,

I have a Parent / Child - domain structure also two different Exchange organizations.

I manage the child domain, and if I want to assign a User from the parent domain to manage a distribution Universal group, what would be the best way to do this ? I've been trying to work around this, but I get errors saying "A referral was returned from the server" when I try to add the user as manage of the group.

Thanks in advance