You can paint the mouth to control the blending of the deformation of the mouth region with the other deformations on the face's envelope. The mouth region is controlled by the mouth operator, which is an envelope-like operator that is specialized for the mouth area.
Click the Face Mouth tab on the Tune panel, then select Paint Mouth Blending.
Move the cursor over the head and it turns into the weight paint tool.
When you paint, values of 1 (turquoise) are where the vertices on the mouth are being deformed by only the mouth operator.
A value of 0 (black) means that the mouth vertices are deformed by only the envelope operator.
Press Esc or the space bar to exit from weight painting mode.
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