djohoe28
Oh, ROJOhound beat me too it! I was going to suggest that, as well as saying you could also use "Pick top instance" because the last one created would be the highest in the z-order (unless you manually change it).
You could also save the UID in a global variable every time you create an instance. Then you have that available any time you need the sprite without having to make C2 loop through all the instances.