iPhoto event dates

I have a collection of photos from my daughter's kindergarten spanning May 2009 to Feb 2010. They were given to us on CD. I dragged the photos all to iphoto and merged them into one event. Though not technically one event, that's how I want to see them. That's fine, but in the event window it puts the event at the date of the earliest photo (May '09). Is there a way I can make it move to Feb '10? I don't want to change any of the photo dates.

 

No, I just want to move one event to a different position. Globally, I'd like it to put events at the latest date if events contain photos from more than one date. At the moment it goes in the event list at the date of the oldest photo.