Setting many sprites of two kinds to same position

So I have two different sprites: colorball and gravball. I have many instances of each. I would like each colorball to have the same position as each gravball.

<img src="http://i.imgur.com/IyWoGlx.jpg" border="0" />

You can see what is disabled actually works, but seems inefficient. I had the gravball's private variable each to the colorball's private variable and that didn't work. I don't understand why. I'm sure someone here can explain what's happening. Thanks!

Add For each GravBall at the top of event 64. The problem is every GravBall is picked at event 64, so it's moving every one. You need the extra step of picking one at a time.

Thanks!