How to edit an specific expression from an Audio Amplitude slider, without messing with other layers?

Hi everyone!

I'm making somekind of "dancing animation" that uses several effects reacting to an audio file.

This audio file is about 8 minutes long, and the effects appear in separated parts of the song... BUT


here's the deal:

I have an Advanced Lightning effect which I could make it react to the audio by adding expressions to the Glow and Conductivity state according to [Audio Amplitude/Both Channels/Slider].

So far, so good; but I need to add the expression to the Opacity and at the same time, having the solid invisible for a portion of the track, fade-in at some point, expression-opacity, then fade out.

so: Opacity 0%, fade-in in expression, stay in expression, fade-out in expression, opacity 0%

The Expression code included is the standard link whip, thus it doesn't fade in or out. *3 because I need it "sharper"

Thanks

thisComp.layer("Audio Amplitude").effect("Both Channels")("Slider")*3