understanding a VCA...
imagine an analog soundboard in a church with four choir mics...
every time the choir sings, we bring up all four choir mic faders...
use scotch tape to attach a pencil to all four faders...
we have now "assigned" all four choir faders to the pencil (VCA)...
when we grab the pencil and raise and lower the faders, all four faders move in tandem.
That is how a VCA works.
Audio signals of the choir microphones never pass through the VCA (pencil)...
The pencil is simply a remote control that remotely controls faders that are (taped) assigned to it.
Instead of assigning all the drum mics to a group which is so common, try assigning them to a VCA instead, that way, as you raise and lower the DRUMS VCA,
the reverb of the drums will also change accordingly, provided the reverb sends are "post fader" as they should be.
That's it.........