[NeoVXR]

ok, it's a sudden, experimental idea..
it should fill something in the mid-range, make it fatter, less child-like(=clean), and more resonant without becoming cheesy. adds some "growling" and kind of doubling effect, but it should be almost inaudible in its low intensity. tune it to tightly melt into the voice, perhaps with a mult channel.
I estimate time constants about and within 100msec if this is within parameter range..
not sure if it works..

did you study the threads about multing and autotune in RnB vocals? this would be the first advice.