Paths, Keyframes, and Expressions

Hi,

Is it possible to change the shape layer path keyframes via expressions? For example:

key(1).value = thisComp.layer("Reference").content("Smile").path;

key(2).value = thisComp.layer("Reference").content("Frown").path;

In theory, the result should be that the path's first keyframe would look like a smile and the second keyframe would look like a frown.

But that isn't happening. Instead, the path has the shape of whichever value is on the last line of the expression, regardless of which keyframe it is at. Am I doing something wrong? Why is this happening?

Thank you so much for your time,

--Saib