Selecting images to display

Afternoon,

I’m creating a portfolio area on my web site. I’ve created an animation where there’s a washing line on screen with thumbnails of my illustrations hanging out to dry. When you click on a thumbnail, the washing line scrolls over and there’s a bigger version of the illustration hanging. Clicking back returns you to the thumbnails area.
I can’t for the life of me figure out how to tell Flash to display just the relevant large image. I’ve got 3 large images “off stage” ready to scroll on but I don’t want to have to duplicte the frames and put in a different image each time as that will uneccasarily increase the file size (especially as the number of illustrations increases).

I hope this makes sense. I searched the forums and couldn’t find anything similar.

Thanks in advance,
pipkino