QC Quick help. How to apply color tool on only one texture

Quick question.

I have a model and the QC has two textures for the model like this:

$texturegroup “skinfamilies”
{ “texture_1” “texture_2”}

I would like to be able to apply the color tool to color only texture_1, but leave in tact texture_2. So if I color the model red only texture_1 turns red while texture_2 stays the same.

I’ve seen people manage to do this before with models, how does one do this exactly? Tried searching with no results.