Outlook's iCalendar support can't do that. When you send the update, you might want to include a note suggesting they delete the old item.

--
Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
http://www.turtleflock.com/olconfig/index.htm
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx

"kirsty" wrote in message ...
i've arranged an appointment as forwarded it as an icalendar to the people in
my office, i now need to rearrange it for the following week. how do i edit
it so that it edits my colleagues calendar as well?