How to use removeChild without declaring the path

programming flash
1

Hey, I was wondering how to use removeChild on movieclips if the path has not been declared, the reason for this is because different movieclips in my game will be temporarily assigned to different containers (background and foreground specifically, behind or in front of the character) and I was hoping not to add another array which included the movieclip’s path (or something similar), so far I have this:

for (var XXX:Number=0; XXX<array_fade.length; XXX++){
    if (array_fade[XXX].alpha < 0){
        **duplicates_bg.removeChild(array_fade[XXX]);**
        array_fade.splice(XXX,1);
    }else{
        array_fade[XXX].alpha -=  array_fade[XXX].fadespeed;
    }
}

So far the movieclips were only being stored in the container “duplicates_bg” but now I’ve started to use the container “duplicates_fg”, I hope this made sense :p, thanks in advance for reading