John HuangZhen offers up his freely available blendShape Management Tool for Maya, HZBS, which provides the tools to allow you to add corrective targets into Maya’s blendShapes with support for most geometry types including lattices.
Blend shape management tool for maya
HZBS Custom Blend Shape Management Tool can also assist in creating reverse shapes for other deformers in the character pipeline, letting you add controllers and targets or create fixed shapes for animated shots, or provide an easy way to break target symmetry.
To learn more about the Maya HZBS Custom Blend Shape Management Tool, check the page here with a download.
