How to blend 2 tracks into one with one control??

Hi
I’ve got 2 vocal tracks I’d like to blend in a unique way, not sure how to do it.

First vocal track is bright
Second vocal track is dark.
Both are roughly the same volume.

I’d like to combine them into one track mixing more bright or more dark depending on which word is being sung.
When I turn up the bright track I’d like the dark one to be turned down and vice versa.

Is there a way to accomplish this without having to ride both tracks up and down equally ?

Thanks

One way would be to combine the two vocal tracks into one stereo track with dark on left and bright on right (or use a stereo group track and send one track to the left and the other to the right using the panner)
Then put a mono summing plugin post panner and use the stereo (or group tracks) panner to set the balance between bright and dark vocal.

blue cat gain.
https://www.bluecataudio.com/Products/Product_GainSuite/