The easiest way to accomplish this given the current setup might be to stagger the times slightly.
For example, you have Event 1 taking place at the same time as Event 2, say 6pm.
When you go to set up the sign-ups, you can make Event 1 start at 6:00pm, and Event 2 start at 6:01pm. This *should* position Event 1 over Event 2 every time on the calendar, and provide minimal confusion and problems (unless someone wants to squabble about the one minute difference). That's about all I can think of for this =)
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. : KeelaDesigner of www.renewal-guild.com