You can set the location of the butterfly sprites from the skateboard class, so the skateboard object can set the butterfly's location in relation to its own location. If they are just images moving with the skateboard without any other purpose, then you can create a new simple actor and assign an image to it. Then move it accordingly. You could also have one actor to display any number of butterflys if you change the image (and position) based on the number of collected butterflys. It is a bit similar when you create an object in relation to an object's position, for example when an object shoots a projectile. But you need to keep a reference to the created object, so you can move it with the skateboard.