Environment: Exchange 2003, SP2 and Outlook 2003

A resource calendar is shared so that users can schedule time with the
upgrades team. The team lead then needs to be able to add, later, the
"attendee" who will perform the job.

Desired process:
1) User A opens meeting request on own calendar, therefore being the organizer
2) Adds attendee type for the resource
3) Sends meeting request
4) Delegate (w/ owner permissions) accepts meeting
5) Delegate opens meeting on the resource calendar, on schedule tab adds a
new attendee (User B)
6) Delegate sends update
7_) User A gets updated meeting request with confirmed time and User B as
attendee
8) User B gets notification of meeting request and accepts

Using the process above, we get stuck at step 5, because the add others
button is greyed out.

We have found that if the resource is the organizer, the attendees can be
modified by the delegate. Is there a permission or configuration that will
allow us to follow the steps above, so that users can be the organizers not
the resource?

Thank you in advance for your time and assistance