Some help understanding nested symbols

I searched around the forums and found some threads about nested symbol animation, but none seemed to answer the question I have. I took the advice on some of the other threads about encasing individual symbols in "packs", where each symbol can be called out by choosing a particular frame. Here's my problem:

My main character's animation is encased a symbol called "boy." Boy is comprised of symbols for his head, his left and right arm, his left and right hand, and his torso. My issue is with the head symbol; here is how I have I have it set up:

Head-->Contains all of Boy's heads on individual keyframes, along with an Eye pack, nose, and mouth pack, keyframed to match the heads on separate layers.
Eye pack--> contains blank eyes, blink animation, and pupil pack.
Mouth pack--> Contains mouths.

Let's say that inside the Boy symbol I want to call his head_up position while he's smiling, with his eyebrows narrowed. I do so; it works out just fine. The problem is that every other keyframe of head_up within my animation will now reflect his smiling/narrowed eyebrow position, regardless of what his expression was before. After some thought, I realized that this was because I was, in essence, editing the symbol itself; with my current set up, I don't think there's any way for me to match heads to different eyes and mouths short of me duplicating the symbols and creating every possible combination of the features. NOT something I want to do with only eight weeks to finish this project.

My question is, what's a better setup for nested symbols? I'm fairly new to flash; a lot of this is a learn as I go sort of thing, which is still pretty bad since, again, I'm on a deadline. I'm thinking what I can do is make the blank heads with noses their own symbol, substitute that for the head_pack in Boy, then put the eye, pupil and mouth packs into each keyframe as necessary. If there's a simpler way of doing this, I'd love to know.