For iClone Morphs Creator you only need to preserve OBJ vertex order and enable Poly-groups on Import/Export (in Blender there are settings for that. Do not know about MAX).
Note: in Blender 4.0 and up vertex order preserved by default. You only need to enable Vertex Groups and disable Split by Objects on Import and enable Vertex Groups on Export.
But OBJ route is very finicky. Each mesh has to be super clean. One loose vertex on one of the meshes may produce a mismatch error in Morphs Creator.
Plus the pose has to match (in Morphs Creator and imported OBJ).
I'd recommend FBX > iAvatar route for iClone morphs.
Export as FBX from CC (save HIK profile prior). Import to your app and morph it.
Export and import to CC as character (you should not care about materials).
Export as iAvatar and make morphs with it in Morphs Creator.