Change multiple levels in an absolute effect proportionally at once (Aka be able to scale an absolute effect like a linear effect)

So say I’m trying to do a fire intensity flicker effect with absolute effects.

I have 8 actions and I set my background as my high point. Every other action is a percentage below that background level. I like this method because it gives me maximum control over the levels of each dip in intensity, and as I go lower and lower with my high point, the effect adjusts to stay within that same range. However there’s no quick way to adjust the levels of multiple actions proportionally at once. Id like to be able to do that when my boss tells me to make the low level less dark, or bring the low level to 20.

As it is right now I have to change the low level of multiple actions separately, I tried selecting all the actions and then doing @/50 but that just changed all the levels to +50%. So I’d like to be able to go from an effect that’s background, +-50%, +-30%, +-/20% to one that’s background, +-25%, +-15%, +-10% just by selecting the levels and typing (@)(/)(50)(enter)

I know this idea is a bit nit picky but it might help some people out. Obviously linear effects are faster in some ways but it’s harder to finesse them. 

Thanks

Greg