"Exit Animations" triggered by timeline

Thanks for all your help so far. Meryem seems to understand what I want. I had a coworker tell me about this same solution. Unfortunately, I'm not willing to do that, because between all my slides and the multiple layers I have, I'd have to duplicate at least 50 layers. In the end, it wouldn't be worth the effort.

I've attached a concept for other people to see. You click on one button to show the objects in a layer, and when the user is done, they click a second button to hide the objects on the layer. (Sorry Phil, I misspoke earlier about animating a "layer"). I can get the objects on the layer to animate on, but I can't get them to animate off (triggered from a user interaction).

Hope it makes sense this time.

Thanks!