Slider to adjust fixtures without dimmer channel

[vector]

Hi all,
Not sure I have this right as a concept.
I have a number of fixtures which dont have a "master dimmer" channel. Just RGBW. (or lets just use the generic RGB).
I can set up a scene, say colour say purple but want to put a slider on the virtual console that can change the intensity ie manually adjust the intensity of fixture or scene .
For eg, I have 2 lights on the back bar and 2 on the front. I want an all purple scene.
I add all the fixtures , setup the colour using the palette but the back lights are too strong, I want to drop their intensity.
Just as the GM slider works in Simple Desk but I want a "sub slider" to only apply to the back lights or a group of choosing.

This is I guess for manual operation. or even when setting up. Switch to simple desk select the fixture (lock the sliders- ratio) and drag them all down a fraction together. Yeah happy with that now dump/save the scene..even that would help.

What am I missing?

[siegmund]

Have a look at the sliders' submaster mode.

[vector]

oh dear so simple, I hang my head thankyou.
I had clicked the submaster button b4 but because no properties or anything came up and I had read about this loop back stuff I thought it was just for that.