AS2 - playing animations depending on what mc's are onstage

Im building an interactive courtroom exhibit which has seven thumbnails along the bottom of the screen that can be dragged up to load a larger image of each into three possible positions above. Once in position, an “Assemble” button plays one of five possible animations, depending on what elements have been dragged.

I need to figure out a way to program which animation plays when its elements are onstage and I am stumped. Im thinking of using an if-else statement but I dont know how to address the loaded images once they have been put in position.

Any suggestions appreciated!