[Viorel Hartopanu]

i Think i can help;)
so first create an adjustment layer in your edit window of your project name it, let`s say “_Fx CTRL” with the checkbox control name it, let`s say “GLOW” after select your comp or layer with your effect press T which brings you the opacity, keep press left ALT on ur keyboard and click on the stop watch now type: value * thisComp.layer("_Fx CTRL").effect("GLOW")("Checkbox");

DONE! I hope is gonna help you! chhers