Making video layers active when other are turned off.

hi guys

I have a question which I hope some can help with. I have a comp with a 10
layers. Is there any way in which I can create an expression so that when the
top 5 layers are off (inactive) and I select them to become active the bottom 5
then automatically become inactive (off) ?

thanks for your help in advance

You can't control the active switch (eye ball) with an expression, but you could
have an opacity expression for the bottom layers that monitors the active state
of the top layers. I'm not sure exactly what relationship you're looking for,
but here's an expression that would set opacity to zero when layer 1 is active:

if (thisComp.layer(1).active) 0 else 100

I don't know if that helps or not.

You could also create a null with a slider expression control, that would
control your layer's opacity. If you figure 100 = top layers on, and 0 = top
layers off, the expressions could be:

top layers opacity = (pickwhip the slider)
bottom layers opacity = 100-(pickwhip the slider)

Then, if you wanted to crossfade them, you could just animate the sliders,
rather than having HOLDs on them.