Expression checkbox to turn EXPRESSION on/off?

Hi,

I'm working on an animation where the elements in a scene are black line art with some of the elements colored in blue kind of "offset" behind the lines. (For example, one character is all black lines but then he has blue for his hair.)
I have a delay valueAtTime expression on the blue so that the motion is also "offset" by 1 frame. The blue shape path points need to be linked to the line shape, so I have an expression on the shape path.

However, they want to have the line and blue shape elements in the scene to do some crazy transformations/transition into the elements in the next scene (which may be something with a different number of points). Is there any way to have a checkbox or something turn on and off the linked blue shape and black lines, and then be able to turn that on again after the transition to the next scene is complete? Is there any better way to do this, with out just duplicating and splitting the layers before the transition? I'm mainly concerned with the client coming back with a lot of revisions, and am looking for anything that would be more of a timesaver for me...

Here's a reference animation for what the boss is sort of looking for as far as the transitions go: http://dribbblepopular.tumblr.com/post/123672162079/blend-for-two-days-in-v...

And a screenshot of an example of what expressions I'm using now.


Thanks!

Thanks!