Lets say there's a 4-day conference, all day event, i add it to my iCal calendar. Is there any way to add additonal subevents to this event, like certain keynotes? Of course i can add them as new events but then i have no way to differentiate them from other events happening at the same time that have nothing to do with the conference. Is there a way to do this in iCal? How about Entourage?