Combining two secondaries, saturation behavior

I don´t know if i oversee something, but i´m trying to get the following in Color:

There are two persons in the shot, one wears a blue jacket and the other a red, i want to select, just the red color with a vignette/ color key combination with one secondary, and with a second secondary select the blue via vigentte/ color key and enhance the red in one and the blue in the other secondary.
Now i want the rest of the image desaturated, but no matter if i use primary in/ primary out or insde/outside of the secondarys, i´m not able to get the desired result. I´m always overriding one of the two secondaries, and get either the blue jacket within the B/W frame or the Red in B/W but never both ??
If i desaturate in the primary Room , the secondarys also go B/W.
Has someone an idea how to fix this, or do i oversee something in Color

Thanks for your help


Manuel Wenger
DOP / DIT / Digital Colorist
Munich - Germany