You just wanna attached them to a parent object? If so, you could use the "Pin" behavior. When you create them at run time, you can set their instance variables to a certain number, and each number correspond to a parent object, and depending on the variable they will attach to their corresponding parent object. Say you have parent object "blue" and you create child objects "blue". Give the children the Pin behavior and create an instance variable, I will call it "relation". Set relation to 1 for example at the time you create the children and attach them to the parent. All "blue's" children should have the relation variable set to 1 at the time of creation.
I have never used the Pin behavior, but, it should do the job, I think. And quite possibly I haven't understood exactly what you are trying do. :P