You can send multiple blendshape nodes created in Maya to Mudbox. In Mudbox, the imported blendshape nodes become Sculpt Layer groups and the blendshape targets within a node becomes sculpt layers under a group. For more information on Sculpt Layer groups, see Group sculpt layers. 
You can edit the imported blendshapes nodes in Mudbox and merge back to the Maya scene without losing the modifications. This interoperability helps you to perform finer sculpting on the imported blendshapes in Mudbox and then merge them back to Maya.
Note: You can send only the sculpt layers inside a group to Maya as blendshapes, or use to update existing blendshapes. The modifications that you perform on sculpt layers outside of any group are merged into the original mesh and target meshes in Maya.
For example, to merge back blendshape modifications to a Maya scene
- Create multiple blendshapes in Maya.
- Send the Maya scene with multiple blendshapes to Mudbox using the File > Send to Mudbox options. Perform modifications on the imported blendshapes (scuplt layers in Mudbox).
The Sculpt Layer groups ensure the details added on a sculpt layer are correctly merged to the corresponding Maya blendshape nodes.
- Update the Maya scene.
The blendshape targets or meshes in the corresponding Maya scene are updated correctly with the modifications.