make my sub keep its color despite cues

hi, in the present show, we use spectra rgbww. We use them in cues in the show, but also in a submaster as worklight. i'd like them to keep their color when used with sub fader. For now, when i cross cues with worklight fader on, the spectra change color depending of cue on stage. How do i have to configure my sub to get the color fixe, no matter the cues going? is this a priority question?

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