I cant not stress this enough. Although i have not the autority to do so.
Your events are redundant because you dont use instances, and you dont know how to pick them.
It is as easy as this:
https://drive.google.com/open?id=0B1SSu ... lRZLUFWVmc
At the same time i show you a proper use of a function.
A function is needed when you have to pick from scratch. And i need to, because the 'on drop' picks only 1 sprite2, while i need to evaluate the others too. So, i have to broaden the picklist. (can also with 'pick all')
A function is convenient if it is a block of events that can be reused with other parameters, when the function can pick the right instance or the right member of a family. In other cases you only dive deeper into problems because the set up is to complicated, especially when using a new object for each sprite.