Button animation

I’ve made a menu with animated buttons. Each button when clicked makes a movement towards a point B. When another one is clicked the previous button goes backwards from point b to its original place on the menu. This inverted movement takes place with if(_root.nm._currentframe == “30”)_root.nm.gotoAndPlay(“back”); , where “nm” is the name of the movie clip and “30” is the last frame of the “on release” animation where the time line stops.
What i want to do is call the backwards animation not only when the animation of the previously clicked button reaches frame 30 but even during the motion towards frame 30 and when the motion is interrupted by the click of another button, i want the backwards motion to start from the current frame it was interrupted. I hope i’ve made myself clear. Thanks:(