I'm new to this site but always in for a challenge

Hoping that I got the photo attached to this reply
Actually I was looking for information about whether it is possible to add an extra color layer to the channels in
PS and how you do it. I worked with a photo from a client and it had an additional red layer in the channels palette(photo is cmyk) to color seats of the car red instead of yellow. I wonder why they did it there and not in the layers palette. Anyone any idea of how and why?
Thanx,
Danii