In the past (2013 SP1), adding a user that was an admin via core service, I could do something like this:
$user.Privileges = 1
but now, with SDL Web 8.5, UserData.Privileges is "obsolete" and doesn't work (shame on SDL for not deprecating it and giving us time to migrate to new API, but I digress). So, using that fails. What's the new approach for marking a user as system administrator? Do I have to explicitly add the new "System Administrator" group to the user?