Select two layers, run the script. A Gaussian Blur will be added to both layers with an expression inversely linking them. Changing the blur of the non-expression-controlled layer will automatically change the blur of its counterpart layer. If you want to change the blur amount, twirl down to the expression controlled blur and change "var inverseBlur = 40 - otherLayer;" to your desired blur amount. Perhaps 100. Perhaps 25. The choice is yours.