I find that when comping CG, you have to make the choice between using the light groups OR using diffuse/spec/sss etc

For instance, once you have adjusted the balance of light groups then you can no longer subtract the specular as it contains the original light group balance, and vice versa.

But I suddenly thought, I wonder if somebody very clever has found a way of using both.

A = Original
B = LightGroups Adjustment
C = Beauty AOVs Ajustments
D = A == 0 ? 0 : B / A ( if A equal zero then zero, otherwise B divided by A )
R = C * D (C multiplied by D)

R is your Result

The order of B and C donâ€™t really matter

In Flame you may need to write a Matchbox for this.

Not a full beauty rebuild, butâ€¦
If you want to use them to tweak the beauty / result you can just subtract them, tweak, and add back. Youâ€™d probably do this after your initial rebuild using whichever set you prefer. As long as youâ€™re not clamping the different light balance you mentioned shouldnâ€™t break the comp.
Or did you already try this?

obviously I dont have your client brief, but if you want work on your cg with out the spec, then subtract it before you adjust your light groups and then add it back on ? if you were asking if you can use light groups AND diffuse/spec/sss etc together then like I said yes, but your going to have ask your CG to supply it, maybe thats the problem? but you can get a all these passes in one clip if you ask?and add and subtract, grade to get whatever your aiming forâ€¦

I realize you may get away without a matchbox. The reason for the D expression is to avoid dividing by 0. You may be able to get around this by lifting the image ever so slightly by a very tiny amount, do the operation and the negating that change afterâ€¦ so regular Comp nodes my suffice. Iâ€™ll test tomorrow.