thanks everyone for help! I really apreciate it.
Was trying to puzzle a bit with all your suggestions, but no luck so far.
I'll try to describe better what I need.
1. I have let us say 15 layers.
2. each layer appears above the previous one and stays.
3. the change of layers is triggered by putting the Object of the layer in the right position.
4. all the objects on the layers perform exactly the same actions and have exactly the same set of behaviors. So the only thing that is different from layer to layer is the object itself.
5. the objects are united in the families on the basis of their behaviors.
that is why I think that there should be a way to make a general algorithm to describe how EACH OBJECT on Each layer should behave without doing so for each object in particular...
I don't mind to send a file with the project so that you could see what I'm talking about - that's really just a project for me to learn how...
Best regards to everyone :-)