Skin > Edit Smooth Skin > Add Influence >
Turn Use Geometry on if you want the influence object’s shape as well as its transform attributes (translation, rotation, and scale) to influence the skin’s shape. Turn Use Geometry off if you only want the influence object’s transform attributes (translate, rotate, and scale) to influence the skin’s shape. Default is Use Geometry on.
Specifies that you want to prevent the influence object’s weights from being changed indirectly, typically because of weight normalization during weight painting and editing (see Holding smooth skin weights). Instead, Maya holds the weights to the Default Weight. Default is off.