Help with sub movieclips appear/disappear

Question

Hey folks, looking for some early feedback. So in a large movieclip that I drag, I have sub movieclips. Due to them being large they cause the drag/flick/scroll get clunky at times. So I thought about dynamically loading them depending on where the main movieclip is based on a Y state. So this seems to work BUT before I go down this long road, there has to be a better way do this. I've bolded the way I'm planning to go about it.
function mouseDownHandler(event: MouseEvent): void {
  TweenLite.killTweensOf(main);
  y1 = y2 = main.y;
  yOffset = this.mouseY - main.y;
  yOverlap = Math.max(0, main.height - bounds.height);
  t1 = t2 = getTimer();
  main.stage.addEventListener(MouseEvent.MOUSE_MOVE, mouseMoveHandler);
  main.stage.addEventListener(MouseEvent.MOUSE_UP, mouseUpHandler);
function mouseMoveHandler(event: MouseEvent): void {
  var y: Number = this.mouseY - yOffset;
  //if main's position exceeds the bounds, make it drag only half as far with each mouse movement (like iPhone/iPad behavior)
  if (y > bounds.top) {
  main.y = (y + bounds.top) * 0.5;
  } else if (y < bounds.top - yOverlap) {
  main.y = (y + bounds.top - yOverlap) * 0.5;
  } else {
  main.y = y;
  blitMask.update();
  var t: uint = getTimer();
  //if the frame rate is too high, we won't be able to track the velocity as well, so only update the values 20 times per second
  if (t - t2 > 50) {
  y2 = y1;
  t2 = t1;
  y1 = main.y;
  t1 = t;
  event.updateAfterEvent();
  if (main.y < 30) {
  main.OFbandTWO.visible = true;
  } else if (main.y < 20) {
  main.OFbandTWO.visible = true;
  main.OFbandTHREE.visible = true;
  } else if (main.y < 0) {
  main.OFbandTWO.visible = true;
  main.OFbandTHREE.visible = true;
  main.OFbandFOUR.visible = true;
  } else {
  main.OFbandTWO.visible = false;
  main.OFbandTHREE.visible = false;
  main.OFbandFOUR.visible = false;
function mouseUpHandler(event: MouseEvent): void {
  blitMask.bitmapMode = true;
  main.stage.removeEventListener(MouseEvent.MOUSE_UP, mouseUpHandler);
  main.stage.removeEventListener(MouseEvent.MOUSE_MOVE, mouseMoveHandler);
  var time: Number = (getTimer() - t2) / 1000;
  var yVelocity: Number = (main.y - y2) / time;
  ThrowPropsPlugin.to(main, {
  throwProps: {
  y: {
  velocity: yVelocity,
  max: bounds.top,
  min: bounds.top - yOverlap,
  resistance: 50
  onUpdate: blitMask.update,
  ease: Strong.easeOut
  }, 2, 0.3, 0.5);
  blitMask.bitmapMode = false;

Answer 1

also if I want to have the item only appear when it's on the stage and be not visible when off it, I figured i'd use a set of y coordinates that when it's between them, change vis to true, when not, change vis to false. But the logic is escaping me. So if I want band "two" only visible when on the stage, would this work?
  if (main.y < 30 || main.y > -400) {
  main.OFbandTWO.visible = true;